www.stcbunch.net is a group of players looking for long games. You can play easily on FICS (for free), which is at
www.freechess.org. No need to pay. Also look into the Team League which runs on both FICS and ICC after signing up on one of those servers. You can get several long, and this is key, important games. The games are meaningful to your team mates, and that is a big motivating factor. It's not too hard to get long games on FICS just by seeking, also. I rarely have to wait more than a minute to get a 30 30 game, for instance.