Currently, the only thing iridium is used for is making quantum armor. I thought of a few ideas.
Speeds up/slows down time.
Uses energy, the faster, or slower you want time to go, the more energy it uses. So 1.5x slower would use 128eu/t, but 2x would be 512eu/t.
Not sure of a crafting recipe, I'm thinking something with iridium plates, teles, and freqtrans. Probably not so great in smp though. Probably wouldn't affect mobs or players.
Like a mass fabricator, but 2x more efficient. Also works with upgrades, and has a built in recycler that automatically transfers scrap.
Crafted with mass fab, adv machine on top, recycler on bottom, 6 iridium plates on the sides