When I did Xlibris I had this ridiculous notion that they could read my book and come up with a great cover. They hesitated too long so I did up a rather crude artwork and sent to them and said do something like this, only better. They took that and put text on it. I said, 'Tell you what I'll get back.'
Anyway; long before this I was trying to construct and model a space-station; because my story takes place on that space-station. I did a two dimentional drawing in my cad software and then extruded that to 3d in my other cad software; yet felt that was inadequate. I joined second life and thought wow I could make and model that here-not; at least not without a few thousand dollars so I could have my own space to play in. I did the next best and got Opensim and a secondlife like browser and started from scratch and did the station and made some characters. Then I finally designed my main character and took some screen shots.
That became the cover for my first book.
Since then I've gone a bit further and used elements from the sim and some stock Nasa and Berkley space photos and use my Corel photopaint and using layers set out to fuse everything together and Corel Draw to create the text and import that onto the cover.
From those I've made the E-cover Paperback cover and dust jackets for hardcover. Definitely have no confidence in the POD cover designers. Although for Xlibris I just give the finished artwork and allow them to put in the text and their UPC image and logo.
I have recently used some stock photos to attempt to play with making covers, but it's not always that easy to find the right match for what I have in mind.
I have some background with pencil and ink art and have a few watercolor paintings I've done. But I'm still tempted to find an artist on some place like deviantart.com to do the work.
deviantart page with some of my work
I haven't updated that page in a while and I have a lot more I could put up there, but it represents a notion of my level of work.