REAPER, short for Rapid Environment for Audio Production, Engineering, and Recording, is one of the professional audio software solutions available on Windows and Mac OS X. While REAPER can work to some extent under WINE, the development studio behind this software, Cockos, is working towards a native Linux port.
REAPER supports VST/VSTI/DX/DXI/AU plug-in APIs, audio and MIDI items, hardware effect integration, a custom plug-in and FX scripting API, 64-bit support, and various other options. REAPER is sold with individual and corporate/organization licenses though the licensing fees are nominal.
More information on the REAPER audio software can be found at REAPER.fm.
The REAPER Linux references were mentioned via this forum thread. The Cockos Forums administrator wrote:
Not much new here, just making sure all of the latest updates work. Might spend some time integrating FreeType though, to get things progressing more (for fun).
If any GDK/GTK/QT/whatever hackers want to make some money, let us know, we'd be happy to put some cash bounties out for big libSwell functionality improvements...