Participationsmarticipation

So it's been forever since i posted here... mostly because most of my recent pieces have been dedicated to this other group in here and mostly because i'm lazy... but this brings up the point of my post.
i'm involved in a few group projects right now, all very modern-like where we are geographically diverse people working on a project together with the premise that we'll actually do more and be more dedicated because you aren't just doing it for yourself, you are doing it for everyone in the group... when stuff is done, there has been great feedback and encouragement from all involved... the problem being, stuff just isnt being done... people will read the replies and judge the submissions but rarely post any of their own stuff. this has happened before.. most notably (for me) with http://checkoutthisband.blogspot.com... at the beginning we had a bunch of people contributing, commenting and i was learning about great new bands (that i now count among my favorites: The Thermals, Califone, etc) but then participation dropped off and i quickly found myself being the only one posting without even getting feedback on my meager posts... the quality of the posts began to suffer and the became less and less frequent... CTOB died. i guess i could always start posting on it again, but i won't.
i love these current projects i am involved in and dont see them dying (for me) anytime soon... when talking to the other members of these groups (or potential members) they LOVE the idea and wax ecstatic about the potential for such a group. then they dont contribute. then i dont feel like contributing.
so..
for anyone reading, what do you suggest? how do you encourage participation without becoming a nag... how do you keep yourself motivated when the proposed source of your motivation doesn't show? Alas.
I'll post some of my recent art soon to get back on a happier note