Blogmeister Ryan put together a list of top commenters since our new administration system came into play in mid-December 2008. And Sisyphus leads the pack. Here's the top 15, including number of comments (which also includes any that may have been deleted). Some, like misjustice, comment more on other SR blogs:

1. Sisyphus, 7086
2. Phaedrus, 5440
3. Cindy_H, 4746
4. Arch_Druid, 4476
5. hmoffsuite, 4470
6. misjustice, 4345
7. Stickman, 3757
8. Cabbage_Boy, 3708
9. nic, 3148
10. moscow_minidoka, 2974
11. Kage_Mann, 2842
12. Bent, 2476
13. hhuseland, 2440
14. JeanieSpokane, 2411
15. toadman, 2377