CellSynth with ReWire for Mac

From Living Memory:

Sync Different! CellSynth addresses several of the main areas in computer music, notably audio synthesis, audio sequencing, sample manipulation, audio processing and automation sequencing. Unlike many of the more conventional software synthesisers on the market, it is compact and easy to use, and does not require detailed synthesis knowledge. Its efficient design means that all functions operate in real-time with low latency, allowing it to be used in a live environment with MIDI keyboards or other MIDI sources. All output can be recorded to disk for use in other software or streamed directly to sequencers such as VST, Logic or Digital Performer. CellSynth is unusual in catering for both musical beginner and expert alike. Whilst the program is easy and intuitive to use, with an on-line manual and tutorial, those with prior knowledge of synthesis are not left frustrated - Best of all it's shareware!