On tonight's America's Best Dance Crew, the remaining four crews pay homage to the greatest VMA performances of all time, including, of course, Britney's epic "Slave 4 U" number. Tune in to MTV at 7pm ET/PT, right before the 2009 Video Music Awards.

This huge gallery contains lots of fun pictures from last night's show in Des Moines. Enjoy!

Photos by Roderick Norman Trestrail II. 

Britney just kicked off tomorrow's If U Seek Britney on her twitter, saying:

On my way 2 Grand Forks!  Follow me & @XL93 for clues to find a pair of amazing tix to my show starting tomorrow morning at 10am.

Stay tuned to both Twitters tomorrow to win seats to Saturday's Grand Forks, North Dakota show!

 Update, Saturday afternoon- These were the clues in Grand Forks' If U Seek Britney.

At 3pm CST by @XL93:
congratulates Angie on finding Rockin' hiding on 42nd St. preparing for Britney tonight! We STILL have tix! Keep listening to win on XL93

At 2pm CST by @britneyspears:
Tonight's the night! Find Rick on 42nd to help Rock Me In! -Britney

At 1pm CST by @XL93:
One of our jox is your key. Britney will tell you who it will be! 2pm! XL Pass to @britneyspears

At noon CST by @britneyspears:
If you seek my best of house seats, Don't come a knockin, just come Rockin. -Britney Pass to @XL93

At 11am CST by @XL93:
History won't wait. Play it now or it'll be too late. -XL93 Pass to @britneyspears

At 10am CST by @britneyspears:
Best of house seats in Grand Forks would B sweet, but u won't find these on any normal street. - Britney Pass to @XL93