Sugar Bytes has just released WOW, a filter-box with 10 Filtertypes, including Vowel Mode, Overdrive and a modulation system. WOW offers a good collection of filter types : High, Band and Lowpass (each 12 or 24dB), Comb Filter, Band Reject, Band and LF Crusher.
The Vowel mode seems to come from their Unique synthesizer (which is worth a try) : 2 Vowels (U, UE, O, OE, A, A:, AE, E, I.) can be mixed via Cutoff, with all available filter types.
The modulators, Envelope Follower, LFO and Step Sequencer, can be mixed in the parameters right-click menus and can modulate each other.
WOW is available as VST and AU Plugin, for Mac and PC and cost 99 dollars (79 euros).
Note that there is a demo version.