Frame: Steel Nashbar generic mountain bike hardtail frame and rigid fork. Extra long seat post to handle my long legs (38" inseam!).
Wheels: combo rim / disk brake compatible 26" mountain wheels. Sun Rhyno Lite rims on Deore hubs (I wish they had cartridge bearings.) I have Forte City ST/K tires from Performance Cycling which I run at 85 psi.
Drive train: This is the most unusual aspect of my bike. It's a 9-speed. 45-tooth chainwheel on an old French TA crank (185mm crank arms for those long legs of mine) driving an 11-34 Shimano cluster. This is all the gear range I need around Columbia, Maryland. SPD compatible pedals from Nashbar. Sealed Shimano bottom bracket. Deore indexed shifter and derailleur. Just having a single gearing to shift up and down on is so intuitive, it's almost like having an automatic transmission. Sometimes I think about replacing this with an internal-geared hub. (It would be nice to downshift when stopped.)
Saddle: Terry Liberator Men's. Very nice commuter saddle. Durable and comfortable.
Brakes: Mafac cantilevers with drilled-out Mafac levers. These are very "old-school" brakes. They require a fair amount of hand strength to operate, but they are as solid and reliable as it gets. Fantastic stopping power.
Handlebars: Old improvised "bull-horns" cut from a standard drop handlebar. Bought for $5 from the parts box of a local bike shop. I use a double-wrap of gel tape covered with yellow and blue Cinelli cork tape. It is so important to be color-coordinated!
Lighting / visibility: Cateye 3-LED front light, 3-LED rear light (on seatpost), with 3" amber truck reflector on the back. (You can see the reflector shining in the mirror behind the bike in the photo above.) Everything uses AAA batteries, and they last a surprisingly long time.
Mudguards (fenders): Yellow Planet Bike "Hardcore". Life is too short to limit yourself to black or silver fenders.
Baggage carrying: Old Eclipse platform rear rack with a couple of Nashbar panniers. I fill these up on a daily basis. One pannier carries rain gear, a change of clothes, a lock, and lunch. The other pannier carries my briefcase-backpack, including my laptop. It's a pretty full load, and this bike handles it nicely.