George Trades Waitress for Actress-Ex

George Clooney could have just about any woman in the world, but there is just something about Krista Allen he can't resist.

Or so say Rush & Molloy, who report "friends" of George say he's back with Allen, whom he dated from 2002-04. He moved on to Lisa Snowden (pretty brunette) and then Sarah Larson (pretty brunette), and now he's returned to ... yes, the pretty brunette.

Krista "admits she just can't get over him," says a pal. Reps were mum.