alexisonfire finch james brown (rip) the libertines nine inch nails oasis reuben still remains off the top of my head.
The three biggest ones for me personally have been Alexisonfire, Gallows with Frank and The Ghost of a Thousand
I saw Nine Inch Nails before they went on their huge break back in 2009, also saw Dream Theater before Mike Portnoy left in 2010.
one that stands out is innerpartysystem and another would have to be Blink 182 (but they've recently started releasing music again!)
I saw Adema in 2003 with their original line-up. There's probably a few more but this sticks out the most.
Taking Back Sunday with Fred Mascherino, his last tour (PR 07) Saosin with Cove Dear and The Headlights Ender (local band that I got to see their very final show as they opened for Good Old War. Sucks because I like them a lot now) Alexisonfire Fall Out Boy