In web development, you come across tools all the time, some are incredible and I was lucky enough to find two today.
Firescope is a firebug plugin that gives you HTML and css help. its really neat 
it looks like this in your firebug
(note to my friend: note the lower case logo!! hehehe)
Another tool that is kinda cool , but I would probably not use that much but the days that i need it I will http://www.scrnshots.com/ they have some tools and a nice api, that you can query and mash it up where ever you feel like. This is what i mean
I hope it helps :)