The TEAC A-2340SX 4-track reel deck has been a faithful workhorse. I bought it used in 1983 or so for a couple hundred dollars (it was more like a thousand dollars new) and used it for everything up to when I got the 8-track reel deck, in roughly 1993-4. It's still more experimentation-friendly than the 8-track because the tape is much, much cheaper.
I am still using it to transcribe old tapes, and if I ever have space for a studio again I will probably keep it around for analog recording and general noodling.
I used it to record:
...and a few other tracks I haven't moved over to woozalia.com yet.