thesis by luc(as) de groot is very large. you can also try meta or fago

http://www.philsfonts.com/showing.html?sku=LF000160X1P1&start=1
http://www.philsfonts.com/showing.html?sku=FF011367X1P1&start=1
http://www.philsfonts.com/showing.html?sku=FF111560X1P2&start=1

>

Don't forget ClearviewOne!

http://www.terminaldesign.com/retail_specimen.php?ID=1001&viewFam=1

You'll find a lot of nice fonts with many weights (like the handsome ClearViewOne), but perhaps a reason to favor deGroot here is that he has an explicit method to the madness:

http://www.lucasfonts.com/lucasfnt/infos/fredtemp/interpol.html

hhp

> I think one should favor a typographic solution based on how it solves a typographic problem, not because of its explicit method, or its madness.

Another one to consider is Giacomo:

http://www.terminaldesign.com/retail_specimen.php?ID=1176&viewFam=1

Sure, but the publication of a method is at the very least a good sign, that the issue has been taken seriously.

hhp

A lot of 'em are kinda pedestrian, but any of Adobe's multiple master typefaces offer an almost unlimited range of weights and optical sizes.

DynaGrotesk from Storm Type has 60 variants, and Hoefler's Knockout weighs in with 32.

http://www.stormtype.com/dynag.html
http://www.typography.com/catalog/knockout/index.html

For what it's worth (which would be very little), Apostrophic Lab's family Republika has 300 variants.