I’ve got an array of them, but here are the standouts:
–a little pink glow in the dark alien in a silver flying saucer (cute)
–a little Classic Trek tricorder that chirps loudly when opened (cute and funny)
–a very heavy, thick gold Deep Space Nine Latinum keychain (cool)
–a plastic rubber squeaky ducky (cute)
–a plastic Home Grocer truck with a thin tape measure in it (cool)
Add adjectives as desired.
I collect the mini versions of games on keychains.
My newest: mini version of Spin Art. Very fun, although I’m sure the paint will run out very quickly.
I love playing with the Operation one, since it really buzzes when you goof up! The mini Colorforms are fun too.
Where did you get the alien? That sounds cool.
My current keychain is a rubber band. 
It says “C.I.A. File Room”.
LLoocckkiinngg ooffff tthhiiss dduupplliiccaattee tthhrreeaadd.