[sdiy] Free stuff - ideas? Also, ringmod schematics?

[Eric Honour]

While driving back tonight I came across a computer (133 mhz), a dual
cassette deck, and a pair of computer speakers (in that order, spread
throughout a neighborhood).  Since they were all free I have no
worries of screwing any of them up, but I can't right now think of
anything fun to do with them... any ideas?

Also, a friend of mine works in a junkyard and said he could get me
car audio equipment cheap or free.  If he isn't a complete flake
(which he often is) I may get some speakers, but would it be possible
to use the car amp as the basis for a line-level amp?  Some car amps
are really high powered for the price I'd be paying (fifty watts x 4
channels for less than ten dollars)... so if it works out, I could
save much money on amps.

One last question.  I know it's possible to make a passive ringmod out
of 2 transformers and a few diodes, but I can't for the life of me
remember how.  Anyone have a link to schematics?  I had one bookmarked
before my computer crashed, but it's gone now...

Thanks as always -
   -eric (who lurked under a different address until recently)