This varies greatly by geography.
In the Southeastern United States, it is not uncommon for some women to address or answer people--even strangers--of either sex with terms of endearment, such as Honey , Sugar , Sweetie , Darling , Baby , etc.
This practice is so intimately associated with "The South," that it will almost always be awkward or at best unusual for someone without a "southern accent" to speak in this way.
These terms do seem to be acceptable throughout the U.S. and Canada when speaking to a significant other or to very young children.
If this is not the way that you are known to speak, it could be awkward to use any of these terms to address a friend.
It does depend upon the genders of speaker and the addressee, and the cultural/geographical/linguistic background of the addressee.
english.stackexchange.com/users/3313/Jay
I agree with Jay's answer, but would add that "Dear Sir", "Dear Mr. Smith", etc.
used to be (still are?)
considered standard openings for formal or business letters.
In this pro forma context, the word "dear" is nearly meaningless.
Perhaps at most, it means "I respect you, and I respect the tradition of opening my letter this way".
english.stackexchange.com/users/3350/Phil Rand
Taking the geographical oddities a little further in Cornwall (South West of the UK) complete strangers, normally women, may finish questions with the term 'my lover'.
IE "
That'll be seven sixty
my luuver" best pronounced with a distinct country burr.
Here in Australia there's an equivalent which is 'Darl' - short for darling, again best pronounced with a good Queensland aussie accent.
In answer to your question many couples have pet names, which are normally toe curlingly cute - fluff bunny, didums etc, but the use of darling, honey etc sounds a little 1950's to my English/Australian ear.
We use mate a lot, as in 'Cheers mate' for anyone we're interacting with - works for friends and aquaintances - but then Australia is known for being very informal.
english.stackexchange.com/users/3363/MrTelly
In the American South, it’s quite common for women to address total strangers, as honey , sugar , baby , etc.
(On TV, black men do too, but I haven’t observed this first-hand.
It might be fiction.)
It’s a tricky thing because you’re taking a very familiar attitude.
If you’re a vigorous Southern woman with heaps of personality, it’s charming.
You’re just irrepressibly friendly.
For maximum effect, you have to give the impression that if the president of France walked in the diner door, you’d call him honey too.
But if you have to ask, don’t call people honey .
Most people don’t, and you especially shouldn’t.
You weren’t born into it.
You’ll stand out.
In fact, if your demeanor towards someone is otherwise professional, and especially if you are a man and that person is a woman, never address them using such terms.
It’s patronizing and offensive, an echo of the sexual attitudes of the 1950s and ’60s.
english.stackexchange.com/users/2249/Jason Orendorff
In Australia and New Zealand you'll hear any of the terms luv , mate , cuz , bro , darl , darlin , honey , sweets , cobber , dear , sir , ma'am and even on occasion buddy , you guys , jokers , blokes , sheilas , and so on.
It seems to depend on the individual as to when and how these terms are applied.
None of them are generally considered sexist or offensive when used casually but that too depends on the context because they can equally be used as terms of endearment or sarcastically.
At any rate, using any of the above terms to address another individual seems better than “hey you” and other less appropriate or derogatory terms such as babe , retard , wanker , asshole , and much worse.
However, even these horrid terms are used quasi-endearingly within groups of individuals, especially teens.
english.stackexchange.com/users/17530/Jake
My mom uses the word 'love' when addressing her close friends.
Like by saying "Thanks, love!
Much appreciated!"
And also sometimes if I thank someone like a store clerk for their help, they will say "You're welcome, honey."
english.stackexchange.com/users/16554/Melissa
I think the word Dear is quite okay while addressing your close friends.
I do that very often
and it's not so awkward.
As for Honey.. that would mean a little more than friends, or extremely close friends who wouldn't mind being addressed anything at all!
In the end it all depends on your relationship with the friend to whom you are addressing.
english.stackexchange.com/users/17154/jdhaar
As part of a new campus initiative, my college's student body had to take a sexual harassment test.
Interestingly enough this test claimed any term of endearment such as, "sweetie" or "honey" was a form of sexual harassment.
I live in Chicago, but in the South Eastern United States its not uncommon for friends to refer to each other in such a manner.
The novel A Confederacy of Dunces , which is widely championed for its depiction of Louisiana accents, frequently includes dialog where friends call each other "babe" and "honey.
"
It's more of a cultural thing than anything else, but as a general rule I would avoid using the terms in language or writing since they can have drastically different meanings.
english.stackexchange.com/users/7888/mwksl
If you use those words in the office then you feel some inclination towards those who you addressed.
Again it depends on geography.
english.stackexchange.com/users/None/
As far as I know  dear ,  darling , and  honey  are commonly used between lovers, but I suppose there are more words like that. What else is commonly used?  Which of these can be used to address a (close/not close) friend without sounding sarcastic or awkward?
Using "dear", "darling", or "honey"  to address a friend
english.stackexchange.com
<word-choice><synonyms><dialects><formality><salutations>
english.stackexchange.com/questions/8203
english.stackexchange.com/users/315/mafu
It can depend on geographic regions. Many southern US states use  a range of terms of endearment such as "honey" , " sugar ",  "baby , etc. although these terms are used mainly for females. There are many other terms depending on the region, such as "my luvver" in Cornwall in the UK and "Darl" in Australia. In fact, Australians prefer the more generic "cheers mate" to greet anybody, and there are many other terms used to salute people including "cuz", "bro", etc. Dear  is also acceptable when addressing your close friends. However, in professional situations, more restrained terms of address are preferred, and some people dislike intimate terms of endearment altogether.   Terms like Honey, Darling, Love are generally acceptable between close friends, especially females. However in certain areas/countries it is more common to use when addressing acquaintances and strangers. Other terms include Baby, Sweetie, Sugar. 
This varies depending on where you live, and also depending on your relationship with the friend you are addressing. However, suggestions include darling, dear, love, you guys, mate, honey, sugar, sweetie, baby, etc. The answer to this question will depend on where you are in the world, who you're talking to and your relationship with them. All over the world, there are a range of different terms that might be usable, such as "darl", "buddy" or "lover". In the American South, for example, it is not uncommon for women to address even complete strangers as "honey" or "sugar".
Southern US, it is common for females to call other people, friends and strangers Honey, Sugar, Sweetie, Darling, Baby between friends and strangers  These names acceptable to call a partner or young children In Cornwall UK, women often use 'my lover' to strangers.  Australians have many terms to address friends and aquintances including, Cheers mate, Darl, Bro, Honey, Sweets. Buddy etc  Terms like Love, Dear and Honey can be used to addressed close friends. 
The answer to this question will depend on the region that you are in. The answer to this question will depend on who you are talking to and your relationship with them. Around the world, there are a range of terms that could be potentially used, such as "honey", "darl", "buddy" or "lover". In the American South, it is considered quite normal for women to address even complete strangers as "honey" or "sugar".