Everyone who wanted to explicitly invite certain guests (we actually had to keep a fairly strict door for a variety of reasons, not least of which was that a good frat party at CMU could have 300-400 people there concurrently) would have to create a text file in their public folder on Andrew, chmod that file to be read, and place with line separators up to 10 Andrew userIDs to be read and compiled by a script.
It worked fantastically, aided no doubt by the fact that our house was ~50% ECE, CS, or IS majors.