TUAW did a nice summary of whats available for the mac side of the world.
5 Mac applications for ham radio fans
5 Mac applications for ham radio fans
Although my work keeps me from spending a lot of time conversing with the world via ham radio (I'm KCØEZH, by the way), it's a fascinating techie hobby. Sure, you can use a wireless phone to call anyone on earth, send 'em SMS/MMS/email messages, tweet, blog, etc..., but there's something rather fun about trying to pluck a faint signal from someone on the other side of planet and coax it into recognizable speech or code.
Many hams are hard-core electronics buffs who like to "roll their own," so it's not surprising that a lot of ham radio operators build their own PCs from parts and run Linux or Windows. However, thanks in part to virtual machines and the general growing popularity of Macs (and iPhones) in general, there is getting to be a sizable population of Mac-driving amateur radio fans.