I've often found myself in the mood to create something, but was at a loss for a theme. - That problem has since been solved. :-) I found a list of 100 different themes for ATC's that someone posted on the craftster.org ATC forum.
I hope to one day be able to say that I finished all 100 of them, but I doubt that day will come for a while. So far I've only done 3 of the 100. Shown here is an ATC and the theme for it is "Dream".