Pokemon Go sites: The Silph Road (nest atlas!), Trainer Tips, Pokeassistant IV calculator, and The Silph Road on Reddit
I'm hooked on Guitar Hero and Rock Band. I worked on the Starpower podcast and occationally visit the official GH and Rock Band sites, and XBox 360.
Poker Listings and Card Player Magazine
Warning: I got hooked on the Hollywood Stock Exchange. It's fun and free, but don't bother unless you have a lot of free time. Here are some of the fan sites:
Kindom of Loathing - stick figure smarminess. And it's wiki.
Boxerjam, hosts the Strike a Match and Out of Order games.
Online games at The Station - includes interactive Wheel of Fortune and Jeopardy!
Netrunner, a collectable card game I played quite a bit in college.