I left my image drive at a friend's house, but later I'll post some pictures. Basically though, anything that you consider to be possible evidence of alien life (intelligent or otherwise) or possible intervention in human history.

I just flushed it down the toilet.

http://xkcd.com/1071/

This is the only evidence to speak of - the size of the universe suggests that aliens must exist somewhere, however, in the same breath, the size of the universe also precludes aliens from being discovered in anything less than geologic time.