While there's a lot of modules based on designs of the "classics", there's still a few old manufacturers out there that don't seem to have seen ANY reissue action. So, let's have a look at some of these...and maybe, just maybe, some developer might see fit to put some of these classics back into use.
WAVEMAKERS: http://wavemakers-synth.com/ Wavemakers was a small synth company that came out of the Ann Arbor scene and which only made a handful of systems. However, the sound of these is...well, sort of like what you'd expect from a West Coast synth that's being made to work in East Coast modes. They had an interesting format, also...both full and half-size modules, but implemented rather differently from the Moog half-size paradigm. Wavemakers made a number of modules that would fit here; just have a look at the site above.
TECHNOSAURUS: They came onto the scene perhaps a bit too early, but their designs were pretty amazing. Again, you see some West-meets-East Coast stuff going on here with their oversized modules. One that looked especially tasty was their Octal Subharmonic Oscillator. Technosaurus also offered some small tabletop boxes, too...the Microcon synth, Cyclodon sequencer, and Effexon multieffects box in addition to their Selector range of modules (http://www.vintagesynth.com/misc/selector.php). No website anymore, though...that got taken over by some domain squatter, apparently some time after they left the business.
POLYFUSION: While there's claims that these will "eventually" be reissued, that claim's been afoot for years now with no discernable action. Polyfusion was started by some ex-Moog guys in Buffalo, NY and gained a decent popularity in the 1970s for their modular line, with the most famous users probably being Toto. Much of the modules are similar to Moog ones, but with a different form factor and some improvements to the original designs. Interestingly, the original Polyfusion actually still exists, but these days they make industrial process/control systems and medical electronics. It's also worth noting that the still-not-really-operational "new" Polyfusion intends to offer modules in the standard MU format, and not the form factor developed by the original firm.
ARIES: Now, a few Aries designs HAVE been reproduced, notably by Nonlinearcircuits, but not very many. They were a New England-based firm that offered both kit and prebuilt gear, up to full systems. Much of these use fairly basic circuits, but a few things do stand out...and as a rule, these are ones that Nonlinearcircuits are reissuing. Aries modules are also very similar to...
DIGISOUND: A British kit company during the 1980s, the Digisound Series 80 modules offered modular functionality but the stability and goof-proofness of CEM chip topologies. Several makers are either reissuing these in Eurorack, such as Pharmasonic, and others are clearly influenced by the Digisound line. Probably their most notable module is the VCDO, a VCO which uses digital wavetables which can be scanned in banks or across ALL banks, by sending the wavetable selector pulses to shift wavetables. This is the origin, in a sense, of things such as the Blacet Miniwave, etc. Both Digisound and Aries used the same 5U form factor and power requirements, which explains why my Digisound 80 has an Aries Power Supply and output module.
SYNTON: The Fenix is still a highly regarded modular. But like Polyfusion, the parties responsible for the Fenix claim to be reissuing this "real soon now"...as in, probably not really ever. The Synton Fenix was a brilliant system with lots of sonic quirks all their own. It's worth noting, btw, that G-Storm released a VCF module based on the incredible Synton Syrinx formant filter, which is definitely one of the great performance filters...it begs to be tweaked! Synton sort of still exists, and they also seem to be the "umbrella" for Tinrs, but the links for the Fenix on their site just recurse back to the main page. http://synton.nl/
Anyone got more? Post 'em!