Here's a graphic bookcase that I love, found on Houzz.com:
And here's a beautifully styled and painted bookcase that DIY and decor blogger Kate, a.k.a. "Centsational Girl" did to her Billy bookcases:
Kate even has an excellent DIY tutorial on making them look built-in that you can read here.
And then of course I see something like these all-black bookcases and I think...why paint them at all??? These ones seen here were featured in the November 2011 issue of House & Home (found on the H&H blog) and they look great dark. Maybe all I need to do is add some crown moulding to the top of mine and choose books, art and decorative items that will display nicely against the dark shelves.
Ah, decisions, decisions. Stay tuned to see what I end up doing!