We've managed to get some frames to stay up with those 3M wall sticker things, but they don't really work for very heavy frames. We have a large blank wall that needed some sprucing up, but knowing we couldn't put up a large frame posed a problem.
After some Internet searching (there's loads of ideas for renter decorating), hubby and I decided to try a fabric wall hanging. We bought a cheapie canvas from AC Moore that was 50% off and some home dec fabric from Ikea. The fabric from Ikea can be a little pricey, but we didn't need much and we both liked the funkiness of it.
I wish I'd remembered to get more "how to" shots, but we finished these really quickly. We cut the fabric out to be a few inches larger than the canvas, stretched it tight over the canvas, and used a regular old stapler to attach it. No staple gun needed, which is great since I don't have one. I had my hot glue gun ready just in case.
We liked it so much, we put another one in the bedroom.
Now I just have to get curtains up in there...and decorate my craft space...and my corkboard and and....it never ends!