A humble request: if you're on a crowded Metro line (shout out to the red line toward Silver Spring) and you can reach the horizontal hand rail that runs along the top the car, please please please use it instead of hanging onto the vertical poles like a lazy stripper.
I'm all of 5'2" tall, so if I can't get a seat, I have two lonely options to avoid hurtling around the car:
1) clutch the vertical poles, or
2) clutch or the handles on the back of the car's seats.
The latter option is not the desired one 'cause it makes seated folk nervous. I guess they think I'm going to punch them in the back of the head or something. Anyway, this option also stinks 'cause when I get to my stop I have to clamber past monolithic commuters hovering in front of the doors while they pretend to read or sleep.
So...do a shorty a favor and take the higher ground (um, rail) when riding the Metro. You tall people can easily push past us midgets at the doors, so we all win.