When my league used Yahoo I kept track of rosters in the off-season using Excel files. I just sent them off to the league in the off-season, and posted the files on a Yahoo groups page.
(Yahoo groups is also a good way to conduct a draft.)
This year my league switched to SportsLine. Except for a couple of exceptions, we are all pretty disappointed and will probably go back to Yahoo next year.
"The game has a cleanness. If you do a good job, the numbers say so. You don't have to ask anyone or play politics. You don't have to wait for the reviews." - Sandy Koufax