Bluezone Corporation has released a free sample pack containing 1 GB of free sci-fi sound effects in 24-bit WAV format.
The sample pack is a 0.98 GB download (1.01 GB when extracted) and contains 120 sound effects in total. The included sounds were handpicked from various commercial Bluezone Corporation releases. Most sounds share a similar sci-fi theme, with plenty of swooshes, flyby sound effects, impacts, radio interference noises, and background atmospheres which sound as if they were recorded on an alien planet. Obviously, these are perfect for use in sci-fi video projects and similar audio-visual work, but I can also see them being blended with other sounds in electronic music production.