Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Quite extensive, 78 pages or so--I'm surprised nobody has posted this before. Contains neat little details, such as a key to the two Chauliodes and Nigronia species.

Link updated (again) 31 May 2009.
ftp://ftp.dep.state.fl.us/pub/labs/biology/biokeys/megaloptera.pdf

new link
is here

 
seems to have moved again
I found a working link off here, looks like lots of good stuff on that page.