I usually block people that keep sending me invites.
Facebook really needs to create a way to block notifications for invites to events. Just keep an updated list that I can look at occasionally. If I could at least block the ones I get on a daily basis from bands that are 500+ miles away from me I might actually start paying attention to the other ones.
On a side note, a couple months ago I got 5 separate invites from some woman's "updating address book" event. You got a new address book? Sweet! So I should be there at 7pm on Thursday...where exactly is it? Oh yeah, it's at Facebook. Let's see if Siri knows how to get there...
