Gary Fisher
Haro
K2
Trick Question:  Which one of these big air tricks have I pulled off?
Cyclone Cycles  A great downtown bike shop!  Near West University.  They deal with all types of bikes.  Their major brands are Haro, Gary Fisher, Marin, KHS, Jamis, Roland, Ventana and Northstar.  One thing really cool is that they deal in USED bikes!  Buying a used bike that's in good shape is an EXCELLENT way to get started in biking so you can get a feel for what you like before you really plop down some dough!  And trust me...95% of the results of your performance is not going to be the bike, it's going to be YOU.  When I first started out on a $300 used Fuji road touring bike (Thanks Cyclone!), I was able to keep in a paceline with triathlon trainees riding $4,000 titanium framed LiteSpeeds.  Don't believe me?  Ask my man, Lance.

Bike Barn Although it's a franchise store operation, it's pretty decent.  I am more familiar with their Kirby store location.

Boone's Cycles A good eclectic and high quality road bike store!  They even have a nutritionist and athletic fitness counselor (for a fee) on hand.  Heck, get your VO2 max measured, even if you don't know what it is!  Downtown near the Medical Center.

Bike Lane  This is a nice bike shop, notably because of their PREMIER bike mechanic, Ken Thurlow.  Ken really knows his stuff and has been in the bike business for many years.  An excellent wheel man!  They are on FM1960 just west of I-45.  On the north side of FM1960. 
376 FM 1960 West    281-440-6100
Bike Companies
Cannondale
Diamondback
Trek
Schwinn
Specialized
Kestrel
You can find a grunch more bike companies and stuff at the following resource sites
Mountain
Road
HOME
Cool Places to Online Shop for Bikes & Related Stuff
Bike Nashbar
Jenson USA
Performance
Best Bike Buys
Price Point
Taylor's
HBC
Northwest Cycling
HABA
GHORBA
Bicycle Clubs in Houston
Total Cycling
Colorado Cyclist
this column has my favorites
Texas Bicycle Racing
Mountain Bike Racing
Racing Organizations
Bicycle Organizations in Houston
If you're looking for Shimano components for either your road bike or mountain bike.  Here is a GREAT place to start to find out what the web prices are today via a free comparison shopping service.  It also displays data for suspension forks by Manitou, Marzocchi, Stratos & RockShox! www.comparisonpricing.com
For tools to work on your bike, there is one brand which is reknown to be the best.  They aren't the cheapest, but they do make very good quality tools and are used by bicycle mechanics all over the world.  Plus they have GREAT explanations on bike maintenance!
Klein