If jam's doing it, that's all important. Record what you jam.
Keep shorthand to give you an idea which jams had some sweet nublets in there, either immediately afterward, or during - while they're still fresh in your head. Hold a whole note, scribble.
Make sure everybody has a recording setup, even a really basic one. Drummer can write with FruityLoops or find another solution, though he may get cranky.
Use gmail to send mp3s of the recordings to whoever wants to run with a specific idea when you're not practicing. Gmail has group chat capability, 20MB limit - can toss mp3's you're working on back and forth and play them embedded.
If you don't have any way to record the jams, and can afford it, I'd suggest the Invalid Link Removed - they're $300, and record video (non-video ver is $30 cheaper, so don't bother). Fantastic for live shows. I listened to a recording once where my buddy walked up on stage, right in front of the bass amp during a show. Didn't clip, and the compression and limiting handled the stage volume freakishly well. For three bills, it's gold.
Lost a boatload of great ideas by not recording jams through the years. You shouldn't have any problem getting 8 songs together if you guys have that going, and use it.