I have finally got a working build environment for my SGI IRIX systems (an R14k Fuel and a dual R12k Ocatane2) and have packaged some open-source software for the fantastic Nekoware project. If you're a fan of classic Unix systems, I strongly recommend heading over to their forums - there's also a pretty strong Sun and HP contingent there among the SGI fanatics!
Anyway - the two packages I have built so far are the fantastic pv (Pipe Viewer) tool and Mercurial DVCS. PV is a fantastic utility that can be used to replace "cat", and displays a progress bar on stderr. See the overview for some examples of what you can do with it. Mercurial should need no introduction; I just had to make a couple of minor patches (included in the tardist and submitted upstream). I've tested both local-only repositories, as well as pushing/cloning/pulling from remote HTTP sites. The only problem I have found is that accessing SSL-enabled repositories produces warnings, due to the old version of Python in Nekoware (2.5). Apart from that, it seems to work great - and the projects do seem to get checked out, it just warns you it can't check the certificate.
Any feedback is always gratefully received; I'm sure there are still some IRIX users out there