Audio Effx for iMovie Video..Any tricks ?

Guys! I am editing 8mm silent film I had "Scanned" to DVD & DV-Cam mini-tape by http://www.dvdinfinity.com.au (had it done the projector,"hot light" method years ago.This cold scan way uses 25% more of each frame we have never seen before on projectors.Their software enhances picture,dispences with grain and projector burn of emulsion)..I need audio effx from the www to enhance the project..I used to use a mini-disc but that is not the way to go in this digital era.To messy..I have just purchased Audio Hijack Pro http://www.rogueamoeba.com but have yet to learn how to use it.As some of my footage is my army days,I have put gunfire into the audio timeline tracks..Looks so authentic.Amazing!..But I need a quick way to grab more short audio effx..Anyone got good ideas of audio sites and any smart tricks to speed me up.(Other than coffee;-) RockyOne Australia