Official ESEA Group Page

ESEA is a 3rd part company that offers a paid service for $7/month where you can play PUG games and scrims on 128 tick servers. Along with 128 tick servers, they also have their own anti-cheat that works better than VAC. ESEA recently released an update to their service to include a matchmaking system which is superior to Valve's matchmaking system in every way (aside from cost).

Less cheaters on ESEA
Competitive round/bomb timers
128 tick servers