A Hammond-emulating drawbar organ of the second-latest generation (ca. 1992). In module form factor, thus basically a Viscount D9 without the keyboard. Identical (except for the colour of the casing) to the Oberheim OB3, which is the predecessor to the way cool Oberheim OB32. This beastie is also available in a stage-organ version with a keyboard, called the Viscount D9, which is again identical to the Oberheim OB3O, predecessor of the OB32O.
The D9e is essentially a solid metal box with wooden side panels and a full set of nine drawbars on top. At the back, there are MIDI In and Thru connectors, mono output and headphone jacks and connectors for two foot switches and an expression pedal. You simply plug a MIDI-capable keyboard into MIDI in, hook up the output to your amplifier and there you are, roaring away Booker T. style.
There's more, however. Solid, LED-studded buttons on top provide access to six sensible preset registrations; you can use a foot switch to switch between the currently selected preset and the current drawbar setting. Other settings include: percussion 2nd/3rd/off; percussion loud/soft; percussion slow/fast; keyclick on/off; vibrato 1/2/3/off; Intersound on/off; Intersound slow/fast. Intersound is a bad, though footswitchable, Leslie simulation; use not recommended.
Pros: Excellent user interface; genuine, robust drawbars. Powerful, pretty authentic sound with earth-shaking bass. Used models sell (as of May 2002) at less than 250 euros, which is nothing (consider the Voce V5 costs ca. 1000 euros new).
Cons: Emulates only one manual, not both manuals and pedals like more modern modules. No internal equalising to make up for the sometimes less-than-earth-shaking treble. Truly crappy Leslie simulation. No chorus. Just one organ type, no leakage adjustment.
Altogether, this kills the instrument for serious jazz organists -- in jazz you will need at least two manuals, usually the pedals, too, and chorus is a must for those Jimmy Smith sounds. Rock/R'n'B(*) keyboarders on a tight budget will love the D9e/OB3, though, especially if played through some rotor cabinet, however cheap (such as my Allsound LC 80 / TH 85).
I've never tried the OB32, but it's the least expensive, and the best-looking of the Hammond simulators currently selling. It's got a full organ simulation plus chorus, too (by the way, it's the only drawbar organ module with the classic six way vibrato/chorus switch). If you like the D9e/OB3's sound and want to get something up-to-date, consider the OB32.
(*) I mean real R'n'B, if you think Destiny's Child is R'n'B, go away and play with your sampler.