Audiffex recently entered the Mac App Store and made some of their applications available for one-click installation.
To be more specific you can now get the Audiffex AU virtual instruments and effects live processor inTone 2 in free (Solo) and paid versions.
The newest Audiffex stuff on the AppStore is ampLion Free - the fully functional 5 channel guitar amp with two speakers.
This app is not just able to process your guitar sound, but you can easily play along with any soundfile and record your riffs.
It is also available as a plug-in module (VST, AAX, AU), but the App Store version only serves as standalone.
