I found this link to be pretty helpful and worthy of being on our resources page.  There's quite a bit of information on here about scales and intervals; it did take me a minute to figure out what in the world a semitone was....but that could be because i'm a bit of a dork.  Anyway, the thing I found to be

most useful, oddly enough, was the table that had the mnemonic memorization samples.  I found the descending ones to be really helpful; I'd always used examples to help me with ascending intervals but didn't even think to use them for descending. The one thing I love about sites on wikipedia is the table of contents that is at the top  of the page.  It makes it so much easier to sort through all the information given.  All in all, I thought this was a good page to have as a resource.