The Twitter blog has been much more active lately and that's a good thing. I found out about this cool twitter stats service via this post on the twitter blog. Here's my twitter usage by month. Clearly I keep using it more and more.
Here's another interesting chart of what time of day I generally send twitter updates.
I can't really explain the late night twittering because I promise you that I do sleep between midnight and 5am. I expect those are from our australia trip and possibly some from trips to the west coast.