I'm already imagining 1000 persons requesting some site to accept bitcoins and then only one of them buying. That'll impress them for sure.
That wasn't very constructive, was it ?
I also thought of that. So that's why there would need to be mods/admins to approve the 'causes'. So a site selling spy-equipment, electronics, usb-sticks etc. could possibly be a good choice, while sites selling knitting kits for grandmothers would not be the best choice.
Also, for instance if partypooker or any other site started receiving lots of requests for using bitcoins, I'm sure they'd take notice, and things like that, you can trust bitcoiners would love it.
Effort needs to be intelligent, you can't aim and shot a random duck at will.
Obviously everything starts with a simple idea, and then it needs to be discussed in a constructive manner, in the end, we'll see if it was a idea that could morph into a real project, or if it wasn't a good idea at all.
Instead of just expressing a negative comment, why not express it as a possible obstacle, and then suggest a way to overcome it, if you've thought of it ? It's easy to find problems, but I rather like to look at them as obstacles. Sometimes the obstacles are too extensive, so the task should rather be dismissed, but a sound discussion never hurt anyone.
In general I don't get put off by comments that are not constructive, but I see far too many people with ideas being put down by others. While I'm a hardened internet person, others may not be, so at least try to applaude the initiative and creativity next time. If a man has 1000 ideas, and act on one of them, it could be enough to create something beautiful.