More Music?? We have:
9 studio albums ~ all with remixes and b-sides
2 remix albums ~ the international versions have extra remixes on them
2 compilation albums ~ new songs, plus tons of remixes and bonus tracks.
3 EPs ~ ITZ Bonus CD, Chaotic, and Key Cuts from Remixed
The Pepsi EPs
Guest appearances on other artist albums/songs like Crazy (with K-Fed), Like A Virgin/Hollywood (with Madonna), S&M (with Rihanna), etc.
Not to mention there are 48 Unreleased songs that have leaked over the years (most of them in full, some are snippets), which in itself is worth about 3-4 more studio albums worth of material and tons of demo versions of songs (we have basically the entire Blackout album in demo form).
If that's not enough you can also listen to the tours remixes or just listen to the full tours, which are alot of fun too.
There are also the live covers like You Oughta Know, Silent Night, I Got You Babe, Something To Talk About, Mystic Man, etc.