It looks from the file mod dates that it's been nine months since I last read anything on Usenet. The date I stopped roughly coincides with my last trip to Europe; I didn't have time on that trip to keep up with my usual net reading, and when I came back the huge pile of mostly-uninteresting messages waiting for me was too big a barrier for me to get back into it. In the bigger picture, web forums weren't enough to make me drift away from Usenet, but RSS and blogs were. I wonder if anything I'd regret missing has been posted there since...
Well no wonder no one ever replied to my post on comp.theory asking about the mathematics behind Sudoku! (If you're curious, take a look here.) But aside from that, you probably haven't missed too much.
Although I have a weak spot for flawed P vs. NP proofs and the like, I have to admit that I spend a lot more time reading blogs than Usenet posts nowadays.