Note
I couldn't find exact dates for Duff's setup, but his gear is listed in order from when he used it.
Basses 
Music Man StingRay (with Guns 'N' Roses)

Mid-80's Fender Jazz Bass Special with Seymour Duncan Hot Stack Pickups (Velvet Revolver)

Duff McKagan's Signature Model Fender Bass (Velvet Revolver [and Guns 'N' Roses I believe])

Duesenberg Hollowbody Bass
Fender Aerodyne Basses
Amplification
Sorry, no pics!
Guns 'N' Roses
-Gallien-Krueger RBH 4X10 Cabinets
- Gallien-Krueger 400RB Head
- Gallien-Krueger 800RB Head
- Gallien-Krueger 2001RB Head
(He didn't use these all at once, he evolved into each head, if you know what I mean)
Velvet Revolver
- Electro-Voice 1x15 speakers
- Gallien-Krueger 2001RB Head
- Two Gallien-Krueger RBH 4X10 Cabinets
- Gallien-Krueger 800RB Head (distortion channel)
- Gallien-Krueger WX15 (distortion channel)
- Marshall JMP Guitar Head
- THD Hot Plate Power Soak
- Marshall 1X12 Guitar Cabinet
Pedalboard
-MXR-80 Distortion Box
-Zvex Woolly Mammoth
- Duff has admitted that he's used a delay pedal live. Presumably a Boss DD-3 Digital Delay
-MXR M80 Bass D.I.
Other
-Straps: Dunlop D-38 DD Straps
-Strap Locks: Dunlop Dual-Design Straplok System
-Picks:

Custom Yellow Dunlop Tortex Picks (.73)
-Strings: Rotosound
Please comment and request rigs!