What do I do when I run out of ideas?
I usually blame equipment first, and location/subject second. After a cigar and some whisky my self-esteem is back up to where it should be!
That said, I don't normally have the issue of "running out of ideas", because photography is such a reactionary thing for me. I find it's best to just...do it. Now, sometimes I don't feel motivated enough to do the work itself...but that seems an entirely different issue!