Resource section is a great idea!Flashkit
has free sound effects, also a massive sound loops section for background music (be forewarned, the page takes a while to load and crashes in chrome, so open with explorer for reliable results).Audacity
is an open source sound editor you can use to edit sound effects or clean up sound loops. I haven't tried the beta yet, but it looks good.
With Audacity check the file size of your edited files before using them; if you edit a previously edited file, the file gets extra data attached and file size increases significantly. Edit original sounds for best results. For small file sizes, split stereo track, make mono, and reduce sample format to 24-bit.