NetBSD runs quite well on Indy systems and the R10000 Octane should be supported in -current.

One easy way I found to make a serial cable is to take a Mac serial cable and cut the handshaking wires. The rest are close enough to allow an SGI to talk to something else.

I use my R5000 Indy with a third party ethernet card as a NAT / IPv6 / DHCP / DNS / rsync server. SCSI drives are a pain in the rear so I put in a 120 gig IDE drive on a SCSI-IDE adapter.