Question: I'm a wanna-be indie developer, and I am working on my first flash game. But, before I even start with the code, I want to know this: When determining the title of my game, how can I decide if it is copyrighted or not? 

For example, at first I thought about "Into the Void" for the title. When I Googled it, I found out that it is a name of a song by Black Sabbath. Is it okay if I use this title, or is it copyright infringement?

Answer: 
If you want proper legal advice speak to a lawyer.

However, as far as I know copyright isn't a big issue with titles for games, especially when it clashes with something that's not a game. Trademarks are something you should avoid though.

However if you want people to be able to find your game on a search engine, having a name that hasn't already been used for something well known is probably a good idea, and that should also keep you safe from any legal issues.
The title of a game isn't copyrighted - it is trademarked. Trademark law and copyright law are related but entirely different areas.

While registration of a copyright is optional, a trademark must be registred to be enforceable (there are exceptions, like claiming an unregistred trademark through notoriety, but these are hard to prove in court). 

Trademarks registred in the US can be researched on <http://tmsearch.uspto.gov/> but keep in mind that trademarks always apply to individual countries. So when you sell a game internationally, you need to make sure that you don't advertise it in any country where the trademark is registred.

Trademarks always apply for specific groups of goods and services. So when I have a trademark "SuperAwesome2000" for toothpaste, kitchen appliances and sportswear, you could still name your game "SuperAwesome2000" without infringing my trademark, because entertainment software is a completely different field. You could even register the trademark yourself, as long as you do it for different product groups than I did. But when you start selling t-shirts advertising your game, we have a problem because you are infringing my trademark on sportswear.

Interesting read in this regard: [Apple Corps vs. Apple Computers](http://en.wikipedia.org/wiki/Apple_Corps_v_Apple_Computer).

But like in every legal matter: **When in doubt consult a lawyer.**