It probably depends what you mean by domaining software. There is portfolio management, name lookup, name suggestion, parking, domain tracking, etc. Some of these are web based software services, others are PC based or scripts for personal websites. Almost anything for domaining can be done with web based applications which seem to keep updated better.
For hosted applications, I find domaintools.com one of my most used tools. I also like fabulous.com's portfolio management.
I don't use much in the way of PC based applications.