Re:Also, CSS debugging help (Score 2, Informative)

I'd love to see something that helped me with CSS layout- a way to put big bright borders around divs and highlight their containing blocks, etc.

The test_styles bookmarklet might fit the bill - it pops up a little window where you can type in CSS rules and have the page you triggered it from dynamically update based on the rules you enter. I put this bookmarklet into my Personal Toolbar Folder in mozilla, so it's just a click away.

There's HEAPS of useful bookmarklets linked off that page too. The javascript shell is amazing.