I bought Photoshop and I'm getting reasonably good at doing basic "game" stuff with it (not shopping photos). I got Inkscape and used it to lay out my tokens and cut paths.
But I might be most excited about learning Scribus. This is an open-source "equivalent" of Adobe InDesign, i.e. a layout tool.
Took a few hours a day for a week to get my 24-page campaign doc laid out, most of which was the learning curve. So then I decided to tackle a more complex document, namely my rule book.