Ummm.....none.
That's it indeed.
Why?
They've been an influence on rock acts like Dream Theater so they could cover something in that genre.
U2 has influenced Dream Theater ?
My 17 yo will be hearing about this. Documentation please. He'll roll his eyes and tell me once again that I think U2 has influenced everyone!! lol!! Well, haven't they? 
Well they are arguably the most influential artists after David Bowie.
I love U2 and they have had a big influence on some of todays bands, but when we're talking all time they are not even close to being the most influential.
The Beatles, Elvis, Led Zeppelin, Bob Dylan, the Rolling Stones, the Who, and others all have been more influential then U2