Links to useful HTML/CSS techniques go here
CSS Hints For Internet Explorer 5
Creating Dynamic Content On Static Pages with JavaScript
Create Accessible side-bars without tables
Creating a Scaled Background Image
CSS Discussion of Practical Things
Images and color profiles on the web
Images and dealing with color shift
More info than you wanted to know about vertical alignment in HTML/CSS
Note that Mac and PC have different gamma, so if colors aren't matching, maybe the gamma setting in png is screwed up. Use PNGCrush to remove it (and it makes the image smaller too!)
Blueprint CSS
Blueprint CSS is pretty cool, and we're just rolling it out in the web apps we develop.