libuv would give us newer CMakes, Node.JS and other stuff. Porting it will require writing actual IRIX support code. Not much work required, but not little either. A weekend or two, I'd guess.
I'm interested in software that ables me to use my SGI's as much as possible as "daily drivers", so my requests will be in that spectrum of software.
Psi (XMPP client) would be fun to have! Version 1.3 seems to be the last version that supports QT4, so it is probably the best contender for being ported. https://github.com/psi-im/psi/releases