Looking for customizable fantasy site

[ajb905]

I run a head-to-head league that is about 15 years old that does bi-weekly games (M-Th and F-Su) where each team selects one game during that period for each player (5 starters). We've always done it by hand since no site (yahoo, cbs, espn, etc) I've found lets us customize to have our schedule and features.

Anyone know of any sites that are extremely customizable or that will work with you to develop a league?