For what it's worth, 2009 averaged out at U$153 and bits, per month 2010 at $203 and bits per month. As for that big drop this year, that's explained by the couple of months I decided not to run the Adsense ads here and they were only on the RSS and email digest feeds during that time. In the end $200 a month isn't enormous money but it does cover household bills so it does come in useful. But the main reason I like Adsense and the reason I've gone back to using the ads here is that it helps the blog pay for itself and makes it useful in its own right. That's just me and my warped sense of values, though.
*Good morning Vancouver :-)