Hello, not sure why you got so little response, maybe because you gave very little info.
13" size is that the maximum or minimum that your friend is looking for?
a decent size laptop I'd say is a 15.6" they come out to 1920x1080 resolution.
The typical gaming brands out there are Alienware, Asus G-series (G53/54/73/74), Toshiba Qosmio, MSI GT series (680/780), Sager NP8100 series (NP8130/50/70). There could be other options out there from custom builders or overupgraded budget models.
Typically hardware would be somewhere in the neighborhood of i7 quad core, nVidia GTX560 or ATI 6950, 8gb ram and 500gb hdd. Everything else comes with default features that are good enough most of the time.
You said you buying in america so I'll assume the budget is in USD and you're looking for USA based websites for the purchase. Newegg is a good overall search source, you can also try manufacturer websites directly or some boutique vendor like xoticpc (NE), but depending on where your friend is going you might look for something closer to him (digitalstorm - CA, or OriginPC - FL)
Good luck, if you got more questions, ask.