1. There is an oscilloscope in your home (you are impressed he knows how to use it, too).
2. He brings the Digikey catalog to bed as reading material.
3. He can quickly read the binary clock on his desk.
4. Rubber chicken.
5. He built his own arcade joystick (which you secretly find rather cool).
6. Monty Python. Say no more.
7. He has projects that require really small components. (which you also strangely find rather cool)
8. He solders. (and you are impressed. you can't solder.)
9. Code can be written by him. Useful code that protects your files. (you look at code and go 'huh?' Again, you are impressed.)
10. He can install computer parts. (you can too, but only up to a point. I mean, you're the one whose heatsink fell off and wondered why your computer was turning itself off. Poor computer.)
11. Airplane...Leslie Nielsen...very funny.
12. Wires. There are lots of wires and cords that you have NO idea what they are for.
13. Can write a program that simulates a Boggle board in under ten minutes (yes, dear, I'm still impressed by that. I love Boggle.)
14. Free computer support.
15. There is a stuffed dead parrot in your living room. And you put it there.
16. You love to wear your "I 'heart' my geek" shirt and wear it with pride.
17. Dave Barry. Though this could be under "Signs you're married to a guy".
Erm...I can't think of anything else, but I'm sure there's more. And I mean geek is a nice way. And if you also know and love a geek, ThinkGeek is a perfect place to buy gifts.
Now remember...engineers are cool. *g*