I'm in a 15 team roto-style keeper league which has an opening right now. Actually, it has one and a half openings right now--one existing team is looking to add a co-manager, and one team is available. The league is Massachusetts-based, with some NY, NH, and other New Englanders in it and is in its fifth season.
The league is mixed 5x5 with some modifications (HR, RBI, OBP, R, Net Steals; W, ERA, WHIP, Ks, Saves+Holds). We're debating right now changing Saves+ Holds to something else, probably just saves or some combo of those and blown saves. 24 man active roster (two catchers, 9 pitchers), five person bench, and an 8 person minor league system per team. Weekly pickups via FAAB, daily transactions. We have been using TQ Stats as a stat service, but will be moving on likely to CBS Sportsline for 2007.
It's a good group of guys, and there's a fair amount of 'baseball' chatter during the season as well as the league stuff, as there's a Yankee fan or two amongst the group. All of the owners are experienced keeper league owners, and it's reasonably competitive but not super-competitive I'd say. League dues are $150, and all but the stat service fee is paid back out.
This year's auction will be in Worcester on Saturday April 7 or Saturday April 14 (discussion still ongoing on which).
If there's interest, send me an email at mailto:email@example.com or post here and I can give you additional details on the rules, keeper stuff, and the current rosters of the teams available. Last year, an expansion team finished second in the league so the structure makes it easy for a team to compete quickly.