NKOTB reunite, and the 10 best and worst career comebacks!













On Friday morning, New Kids on the Block will be performing live on the Today show for the first time in 15 years. Their new single, "Summertime" is available on iTunes and they have a massive summer tour scheduled… but we're wondering just who is buying tickets? Would you see them for the sake of nostalgia? Check out some behind the scenes rehearsal footage, along with 10 of the best and worst career comebacks after the jump. Robert Downey Jr. - This 80s bratpacker turned drug user went to rehab and bounced back with a slew of films, including the latest blockbuster mega-hit Iron Man.Cher - This babe must have nine lives! With on-and-off musical, TV and film success in the 60s, 70s and 80s, we figured all the ups and downs had taken their toll on Cher. Then on her 23rd (!!!) album in 1998, she landed her biggest hit ever with the Grammy award winning "Believe." And now? She's holed up in Vegas. But hey, at least there she can wear all the Bob Mackie she needs! Flavor Flav - VH1 resurrected this rapper via several reality shows, but now at nearly 50 years old his new sitcom, Under One Roof, is actually legit! Who woulda guessed? Mariah Carey - She went from mental breakdown and Glitter flop back to chart and record-breaking singer at the top of her game.

Patrick Dempsey - As cute teen star known for rom-coms, Dempsey had to wade through a mass of mediocre performances before reaching the pinnacle of his career as Dr. Derek "McDreamy" Shepherd on Grey's Anatomy.

Smashing Pumpkins - We were intrigued to hear about a reformed band, but with half the members gone and that whole Alt. rock vibe left in the past, it seems only die-hard fans could appreciate their work.

The Spice Girls - We were psyched about their reunion tour, but tickets were expensive and now it's all over. Better left a memory.

Mike Tyson - He got a hardcore facial tattoo and bit off someone's ear. Sure he's a household name again, but at what cost?

Britney Spears - Umm, what comeback? Her performance on the VMA's was supposed to make us like her again. Still with TV appearances and staying out of trouble, perhaps slow and steady will win the race.

Jennie Garth - This 90210 star had some crappy TV performances and a stint on Dancing with the Stars. It will be interesting to see how she fares on this fall's 90210 spin-off.