I'd like to mention:
PolyGlot, a computer program for organizing (con)langs and generating words, with support for things like logographies and a quiz generator. My biggest problem with it is it doesn't handle Unicode input super well on Linux, so sometimes i have to copy and paste phonetic symbols.
Omniglot, an encyclopedia of natural and constructed writing systems. Good if you need inspiration for your own script.
@early_riser's work on xenolangs or exolangs. Most conlangs are made with humans in mind, or with Humans-But-With-A-Weird-Forehead (see most Star Trek aliens), which is about the same if what you're interested in is speech organs. It's rarer to find someone who considers what a more realistic alien language would sound like.