Testing Paragraph Density
TypeTester is a very nifty website that allows you to test what different fonts look like in your browser. Beyond that, though, it allows you to compare the affect of different css effects on your paragraph density. Do I like impact 1.3em with 3px tracking? How does it look with 1px tracking, but .25em wordspacing? This site allows you to find out as quickly as you can manipulate some dropdowns.
TypeTester: Compare fonts for the screen [via Design Reviver]
Typetester is an excellent tool for previewing text in a browser. I've recommended it a few times. I'll definitely have to subscribe to Design Reviver. Looks like another great SmashingMagazine-style resource.