I would like to see Catherine Wheel get back together since they were "parked" back in 2000 ("parked" being the band's term for disbanding).
Creedence Clearwater should be revived as well.
The Cult needs Jamie Stewart to rejoin.
Masters of Reality needs to reform with Ginger Baker back on drums (maybe Clapton will sit in on a number or two!!! That'd be sweeeet.)
Hey, The Sweet should do one last Ballroom Blitz while we're at it.
Elastica Redux would probably go over well in today's alt-indie climate (their debut album back in '93 is a blueprint for everything post-Strokes).
Erik B. needs to get back with Rakim (yeah, I'm dating myself thoroughly).
And what about Faith No More (no wait... Faith Yes More!!) circa the
Angel Dust days? Another blueprint album, but for the Rap/Metal crowd.
Screaming Trees, Soul Coughing, and The Stone Roses... all obviously need to happen. Too many great tunes that need playing.
Two of my all-time favorites, Swell and Six by Seven, would override any of the above if they were to get going again.
And finally, it would be great see bands like U2, R.E.M., and even Our Lady Peace reunited with their missing cajones. Now that would be something.