I go by 3 aliases these days:
Nascar241993: When we (my family) switched our internet service to AT&T, this became my most common username. At the time of the switch, I was, and still am, a Nascar fan. The name itself has 3 meanings. Nascar=Nascar fan, 24=Jeff Gordon, my favorite Nascar driver, and 1993=my birth year.
Skyhawk71: My second common alias. If I recall correctly, it was my attempt at trying to change my username to something that won't be ridiculed as much, cause pretty much going by any username with "Nascar" in it has a (now uncommon) chance of people ridiculing it.
Nighthawk71=Very uncommon alias. I only use this alias on MWLL and MWO, and (possibly) Battlefield Heroes. Prior to MWO (possibly the first instance where I used this alias), I used to go by the callsign "Nighthawk" on a freeware flight sim/combat flight sim "YS Flight".