If you don't have the money for Photoshop and would like to keep that eye-patch off (you do right?) then I would have to recommend that you check out Gimp. This is a free graphics program that is extremely versatile and has quite a community built up around it. All of the graphics that I have for my project I made myself using Gimp 2.2.
I'm definitely not a wizard yet using Gimp (or any digital graphics tool) and I still prefer pen and ink on paper still, but I'm really starting to like making digital art as well. I've been trying VERY hard not to spend much time on my graphics because of the deadline, but it's been a struggle and I think you can tell various spots where I got a bit distracted working on a graphic and others where I stayed focused on the deadline and not on the artwork.
So why did I take the time to pimp out the Gimp? I had to make some new graphics tonight for my last and final level "Caverns and Leviathans". Currently I have the first "cavern" loading and Bob can wonder around and explore the rooms. I did a new scrolling technique tonight for this that I think works pretty well (it's not exactly like Gauntlet, but it's similar). Time to get back to finishing up the graphics now so that I have some things to populate the "cavern" with.
Oh and in case I forget tomorrow or don't have time to post, to all you father's out there, here's to a Happy Father's day! Hope yours is a good one.