A number of years ago I build a grid drawing tool as a jQuery plugin, it's still available here: <a href="http://gridbuilder.kilianvalkhof.com/" rel="nofollow">http://gridbuilder.kilianvalkhof.com/</a> Might be useful to other people developing locally/designing in the browser like I do.
NeatGrid is a simple HTML5 canvas application for UI designers to easily create pixel-perfect grids in the browser. I created it over the weekend to scratch my own itch. If you happen to have the same need to draw grids, please give it a whirl. Cheers!
That's pretty cool, although it took me a minute or two to see where the download button was (I was confused I couldn't right click and save as) but I guess thats canvas for you