Here's one that's been often-imitated-never-replicated... the Dist+ made in onto some big records in it's day. It's driven by an op-amp and germanium transistors, so it's got a really particular tone: smooth lows with heaps of clarity through the top end, great note separation and a certain grungy attack. Classic for a reason.

Model: MXR Distortion+ Pedal
Made: USA, mid 1990s approx (serial H7-47527)
Type: distortion
Power: 9v power supply (not included, non-standard adaptor) or 9v battery (included)
Equivalent new street price (approx): n/a 
Mods: none
Accessories: no box or manual
Condition notes: used, few minor marks, very good condition