Bungie Pro
From Halopedia, the Halo wiki
Bungie Pro is a 12 month subscription you can obtain by making the transaction over Xbox Live in Halo 3, for 750 Microsoft points. Bungie Pro enhances the players' File Share from 6 slots and 25 MB to 24 slots and 250 MB in Halo 3. No word yet on whether or not it will carry over to every other game Bungie develops.
