If you're looking for retro additions to your virtual-synth kit, Big Tick Audio Software (http://bigtick.pastnotecut.org) might be just the ticket. Its roster includes standalone and VST plug-in instruments as well as VST effects. All offerings are Windows compatible; some are also available for Mac and BeOS.
Cheeze Machine provides convincing emulations of the ARP Solina and Crumar Performer, while Ticky Clav emulates the Hohner Clavinet. Both are free VSTi plug-ins for Mac and PC. The EP-Station (Win; $39) isn't exactly a Wurlitzer or Rhodes emulator, but its FM-modeled sound can be used to lay down an electric-piano groove. The latest offering, Angelina (Win; $39), uses formant morphing and shifting to produce fat, breathy pads. Angelina can be used as a standalone synth or as a VST instrument.
Big Tick Audio's flagship product, Rainbow (Win; $60), is a 4-oscillator synth capable of producing a wide variety of leads, pads, and effects. Rainbow starts with four multiwaveform oscillators. Each oscillator can frequency- or amplitude-modulate any of the others (as well as itself), and each has a level envelope and waveshaping capabilities. The oscillator mix passes through a multimode filter with a dedicated envelope generator, followed by a stereo chorus. Rainbow also sports a 16-step sequencer and pitch-envelope and portamento sections.
Big Tick Audio Software also offers four free VST effects plug-ins. NastyShaper is a waveshaper capable of subtle to extreme distortion effects. Hexaline and DualDelay are stereo delay processors for short and long delay effects, respectively. Makunouchi Bento ring-modulates incoming audio using sine waves of randomly varying frequency.
The MP3 file “PassTheCheeze” on EM Links combines a Rainbow tubular-bell patch processed by DualDelay with a Cheeze Machine track processed by Hexaline. Rainbow is triggered by its built-in step sequencer.