I used Excel a lot, but it really falls down on some departments. Of course, it has good things to it, and especially criative people, like Roi, can make awesome use of it. Nowadays, though, I use Inkscape; though the basic grid I still steal from Excel, since I'm too lazy to actually make one in Inkscape (though it is not difficult at all, just tedious work).
Inkscape, for me, does the basic stuff that I need; circles and lines (yay, I can put people and walls on the map =P), along with letters and such, and some nifty features for background, coloring and such. It's pretty basic, but's it's all that I need.