From 1880 until 1970, thousands of bird-watchers in the US and Canada sent in cards listing the dates when migratory bird species first showed up in their area. These cards were bundled up in string and stuck in boxes. Nothing came of it, until a couple years ago when it occurred to someone that there's a LOT of data in those six million cards and they really should be put into an easily accessible database.What is Phenology?
Phenology is the scientific study of the relationship between natural phenomena (flowering, breeding, migration) and climatic or seasonal changes.
Since these were mostly handwritten cards and not very standardized (sometimes rather idiosyncratic, actually), they have to be entered individually. All six million of them. Some volunteers have been scanning them so they can be sent out as image files to anybody with an internet connection to input the information.
You don't need to know anything about ornithology to do this (which is good because I'm probably one of the few bird-watchers on the board) and you can put as little or as much time into it as you want. I've been trying to do five a day when I get home from work, which takes less than five minutes. Free to sign up (and registration is pretty much automatic), and there's a fifteen minute intro video and an FAQ to answer questions. This is possibly the laziest volunteer work ever since you don't even need to go somewhere else to do it.
I put this in SLAM because it's science but it can be moved if it'd be more appropriate elsewhere.