I typically search for event ideas that are unusual and out of the box. I think that Youtube is definitely a great source of this sort of ideas. All you need to do is go to Youtube and do a search for "event suggestions" and you will see several hours worth of clips with numerous wonderful suggestions. The trouble is, who exactly has enough time to see them all? Thus I am on a regular quest to compile some notes to save me and also perhaps other people some time.
Here is an awesome video with some insane party ideas - https://www.youtube.com/watch?v=wUlJSgYGmFw
I hope you see some good tips for your next event on Youtube!