The other day, I used the word themself during a lecture and on the spur of the moment, conducted a brief poll of whether the class would use it or themselves to refer to a singular individual.
Here's an example of themself with a singular referent:
I always use themself because it is singular to match the semantic singular of the referent, and also because I like to upset Word's spellchecker whenever possible. But themselves is plural to match the grammatical plural number of the pronoun: we always use plural agreement on the verb, too, never singular. Spellcheckers disagree with me on the use of themself and give it a red squiggly.
The results from my class were overwhelmingly in favour of themselves, with only one of the group saying they'd use themself, but then English Language and Linguistics students are a fairly linguistically conservative lot (this changes if they grow up to be linguists, but many of them are in it to be writers or teachers). I followed this poll up with a twitter poll:
As you can see, it was pretty equal with themself ahead by a narrow margin. I predict full matching to logical number before much longer. Here's Stan Carey's post which is more detailed on the history and usage patterns of this word.