Wow! I impressed myself today! ;) I was trying out a software called Pixelmator, to see if I could create a more professional-looking banner for my site. A few tutorials later... voila!! (Scroll to the top of the page). While I was at it, I re-designed the banner and logo for my Etsy shop as well. So cool!!
I've been wishing I could take some design classes, but haven't really found the time or money to do so. Luckily there are some very helpful Pixelmator tutorials on their website! I learned how to do variant grades and also bubbles. Fun fun! :)
Long story short, if you're looking for a Photoshop-esqe graphic design app for the Mac, this one seems like it could do the trick. I really know nothing about Photoshop so have no idea if this could do everything for you that you're used to Photoshop doing... but... for me, it opens up a world of manipulating text and photos that I didn't previously realize I could do!