(This is probably mostly of interest to WMFers, but I thought I'd post it extra-publicly since transparency is good and so is peer usage. Whee!)
A while back, Toby pointed out to me the fact that I keep having to implement the pageviews definition in different forms because there are always different questions - and that making sure everything works nicely together, every time, is time-consuming. It'd be a lot better if there was just a library of standalone pageviews functions, which would also give us things like unit tests.
Toby is usually right, so I put together https://github.com/Ironholds/pageviews . It contains a sampled log reader, a fast implementation of the pageviews definition, an "is this to the mobile web, the desktop site or the app?" request tagger, and a host of other things. Hopefully it'll be useful to someone other than me, although I'm okay with it just being useful to me :)