To recall the basics, OSS and ALSA can be thought as device driver of a sound card. A sound daemon as JACK uses these driver to perform low-latency editing and mixing.
While it's possible to use VST (I don't know how it works) there exist native plugin interfaces: DSSI is for virtual instruments, and LADSPA is for filters & effects - furthermore the next genration of LADSPA is in development and called LV2.
If you're like me, you alwayes sufferd having no great audio tools. While this is still true, the situation really has changed to the better. The most notably programs are:
- Ardour is definitely the flagship, and a professional hard disk recording program. It's comparable to ProTools, belive it or not, and finally has MIDI support.
- Rosegarden4 is probably the most popular MIDI sequencer, and also supports audio
- MusE is another popular MIDI sequencer, and also audio capable
- Wired is fairly new (haha) but a very interesting hard disk recording project
- Audacity is a very good and complete wave editor
- ReZound is another great wave editor
- Sweep is yet another great wave editor
- Skale Tracker is a cool Mod tracker for die hard old school computer musicans
- SoundTracker is another advanced Mod tracker alternative