A Finnish computer magazine called MikroBitti happened to have an article about music programs the other month. Programs listed are:
Cubase SX
Logic Pro
Magix Music Studio
Renoise 1.5 (free of cost+50€ registration unlocks asio-support and ability to save songs as wav files)
Image Line FL Studio 5 (formerly known as FruityLoops, 4 versions available, prices go from 49$ to 399$)
Arturia Storm 3.0 (149€)
Propellerhead Software Reason 3.0 (the most expensive one, 449€ and a software to make your own loops costs 229€)
These are all Windows software, some are also available for Mac. There are some other only Mac programs which I haven't listed. If someone wants to know the name of those programs just ask after 'em here.