This page details some components I've encountered that I feel are of particular interest (to me at least). So far there's just a few of the components I'm using with the speedo project, but the list will grow over time.

TPIC68595 SIPO shift register
This chip is a serial in, 8-bit parallel out, open drain, high power shift register. It can sink up to 150mA per output although the LEDs in this project only need up to 30mA.
( 335k)

ATS177 hall effect sensor
Most hall effect sensors have outputs that require amplification and hysteresis to be added which in turn means extra circuitry, usually in the form of an op-amp and some discrete components. The ATS177 has all that built in plus an open-collector output to boot.
( 124k)

After using this sensor I found an interesting quirk. Most sensors activate when a magnetic field is near regardless of the polarity of the magnet, then drop out when the magnet is removed. This one seems to pull in with N and then pull out with S (or vice versa) so for example of you just have a single magnet poll swinging past the sensor you don't get pulses. With my speedo I just used two magnets on the tail shaft, one with S facing towards the sensor and the other with N.

2.3" LED 7-segment display
These are available from many sources and have to be seen to be really appreciated. You gotta luv a big LED. Each segment has 4 LEDs in series giving it a forward voltage of around 8v so you can't use them on a 5-volt project, but for a vehicle they are just the thing.
( 463k)

Serial input 4x 7-seg display
These are from Sparkfun and can be controlled with just a single serial signal which saves an incredible amount of wires, design time, and multiplex programming.
( 67k)