Question: If I'm making Homemade Jams/Preserves, how long will they last?

Answer: 
The [Good Eats jam episode](http://www.goodeatsfanpage.com/Season2/Jam/JamTranscript.htm) suggests 2-3 weeks if you don't actually preserve the jam in a home-canning kind of way and about a year if you do.
There's also freezer jams, which can easily last a few years in a deep-freeze without losing much quality. They're well sealed, so there's little moisture loss / freezer burn, there's little loss of quality aside from the initial freezing, and you don't have to worry about mold or other organism growing in the freezer.