Here are some bass related toys that I happen to like.
This is one of my favorite toys. The Hipshot is a special tuning
peg with a lever system that lets you tune a string down a few
notes at the flip of a switch. Normally, you set this up on a
four string bass so that you can quickly tune the E string down to
an open D. This is a very cool and common application of the
Hipshot, and I have one on all my four string basses.
You can kind of see the lever sticking out from behind the
headstock of my Fender Jazz basses in that picture up in the left
corner. To use it, you just reach up with your left hand, and
flick the lever with your thumb in a very fluid motion. The low
note is tunable, so you're not stuck with a whole note de-tuning,
but the open D tends to be most useful for the songs I play. It's
almost as easy to flick back up to E, and the Hipshot stays in
tune very well in both the D and E configuration.