You can do pretty much anything you can do on any other unix box with Irix. Run firefox, pretend to do work in Open Office, etc. Run apache, snort, blah blah. It's just another unix box with weird hardware.
I recently gave away all my SGI gear, I hardly ever used it, and I didn't really need a pile of antiquated gear in my closet. I also have gotten rid of my dec crap and my sun boxes. I don't use any expensive proprietary software on the nix machines, so it doesn't make sense to keep the old dinosaurs around.