Geek24 has compiled an interesting collection of licence plate pictures of cars that are obviously driven by geeks. Some Farkers have also contributed to this growing geek licence plate collection which includes car numbers like HTTP, XML, MS-DOS and even UBER-GEEK.
If you like to know more, Wikipedia has a comprehensive article on US and Canadian Licence plates. There's even a Wikipedia entry that has a complete list of US State license plates. Some excerpts from Wikipedia:
Motorists are given the option of extra-cost vanity plates (also known as "personalized" or "prestige" plates), which are licence plates with a custom serial (sequence of letters and/or numbers). In California, motorists may order symbols - a heart, hand, plus sign, or star - on one type of specialty plate.
In some jurisdictions, vehicle owners may also pay extra for specialty plates. With these, the plate serial is chosen by the licensing agency - as with regular plates - but the owners select a plate design that is different from the normal licence plate. For example, an alumnus or student of an area university might get a plate with the school's logo, or an outdoorsman might decide to pay extra for a plate depicting a nature scene.