I don't know how best this can be done. Do we create a WikiCommittee whose job it is to track users and drop comments on their user page? Do we ask a codejunkie to write a script to autogenerate certificate messages? Help me out here, allies. Whatever we do, if anything, I offer my assistance, because the more welcome we make good writers feel, the longer they stay, and the more welcome we make weak writers feel, the stronger they get.
What we need, quite simply, is for people to drop notes on other users talk pages saying "hey, that's some great work you've been doing there!" I've been doing some of that myself, _I_ enjoy doing it, and I'm sure that the recipients are happy too. So my advice: more of that. Less talking on mailing lists about awards and certificates, less organising of committees, just get out there and leave the personal message saying "well done!"
I'll admit, my editing tends to go in spurts: I'll spend a day or two creating swathes of new text (creating or greatly expanding articles) -- then I'll spend another three to ten days doing "housecleaning" - typo patrols, Cleanup pages, disambiguation, lately the Orphaned Categories page. Why? Because I hope against hope that the major contributions I made will be at least be noticed to the extent that someone fixes a typo or adds an external link, and I wait, patiently checking my watchlist, for a few days before I'm convinced (and discouraged) that a new article has vanished into the ether. It certainly feels like the housework gets more credit; at least, I'm more likely to get feedback when I clean up someone else's article. (I know, I know about article ownership.) I'm not exemplary about complimenting people either (and it's always easier to do so via the edit summary than actually going to their user page), but I'll make more of an effort. I just wanted to add my two cents -- I've been a steady editor for a year and a half, and I know exactly what others are saying about feeling like giving up sometimes because no one notices what you do unless you're a troll, or deliberately seek out controversial areas, or participate in every policy discussion.
the quiet one in the back, Catherine http://en.wikipedia.org/wiki/User:CatherineMunro