Some birds can tell they're looking at themselves in a mirror.
[Prior&al paper at PLoS Biology]
This is a version of the mirror test, used to gauge self-awareness.
There are now at least nine species where this has been observed; this is the first non-mammal to have unequivocal results - and there are a number of other bird species that I would be utterly unsurprised if they had similar results.
You have to wonder - do they have a theory of mind? From what I've seen from certain corvids, I would have to suppose that they do.
As the wikipedia link (which has already been updated to include the new information) points out, it's not a suitable test for all animals, so there may well be some creatures who don't perform at the mirror test who are nevertheless self-aware.