Can you explain more? I've got no clue what a "time bank" is or how it would work (or how I'd use it)...

The wikipedia article is actually pretty interesting. (i.e. thanks for derailing my morning Mratthew ...) Isn't there a problem in that not all hours are created equal in terms of effort and sacrifice? In our case, for example, an hour of fixing memory leaks in newbie C++ != an hour play-testing someone's nearly finished game.

It's an interesting idea and I don't mean to impede creativity, but I would worry that it'd become a distraction. And for some, even a goal in itself to simply earn "points" endlessly for "that big project" (which may never start) rather than encourage a less formal cooperative online community. The "reputation" thing here is more than enough "score-keeping" for me personally. The Wiki article warns about overhead/cost of keeping it running, and that's another thing that makes me hesitant.

If all you want to do is encourage development projects, I put an alternate type of suggestion (less "gamey", no pun intended, and more "gamedev") I dubbed a "team-building/matchmaking" service, similar to the old neverwinterconnections.com site. (That site was used to match up various Neverwinter Nights players and GMs with similar interests and play styles to allow groups of people to form small gaming circles.) If it's modeled after the NWC system, that moves some "overhead" to the community sort of like a rating or online review website. (Ex. If a ranking system is needed, use a rating system like "Would you work with this person again?", "This person was particularly creative.", "This developer was dedicated and motivated." etc.)

I tried to describe it loosely here, for what it's worth:

http://www.gamedev.net/topic/636615-gamedevnet-2013-what-do-you-want-to-see-from-the-site/page-3#entry5028247

I'm sorry mate, but i just don't see it working. their are numerous problems, most notably is difference's in skill/capability's, not screwing up projects by accident(such as inducing more bugs by trying to help and fix another bug.). people abusing the system(how do you monitor that their work is actually equal to one time hour, what is the baseline of skill, perhaps you could say "implementing x function = y hours").

at the end of the day, you need a strong community to be willing to do it, and this is not to knock gamedev, but i don't see that particular type of community here. that is not to say it isn't a selfish community or something, but it's to say that people are more interested in their own project's than to help with someone else's in the hopes that it'll be "paid" in turn for their project.