There are lots. Not to be self-serving, but I post all the best links I find on www.thehipperelement.com, if you feel like scanning through them.
But a few, off the top of my head are:
- www.alistapart.com - http://www.uie.com/articles/ (run by Jared Spool, I think) - www.smashingmagazine.com is a bit hit and miss, but what they lack in quantity they make up for in quantity. - www.unbounce.com - www.goodui.com is a good, quick, visual reference for best practices. You could make a career just from enforcing some of those, haha.
And these two books would lay a good foundation in general:
- "Web Form Design" by LukeW (his blog is also interesting) - "Don't Make Me Think" by Steve Krug
If you only spent a few hours on those you'd be ahead of the game. And if there is anything you feel is missing from the world, let me know on Twitter and maybe I can write something about it. @HipperElement
Hopefully that helps.