Jimmy Kimmel went on a tirade about excessive Facebook friends a few weeks ago, and it's attracted lots of well-deserved publicity.
Original tirade - November 3
Follow-up - November 4
How to unfriend - November 9
Article with useful reminder about creating friend "lists" to control what info you share to certain groups of people
As for people with endless game announcements, I've ignored their game posts, and as for people with non-value-added posts ("cooking dinner haha") I've ignored their posts entirely. And I haven't been afraid to unfriend people whose posts are endlessly depressing, depressed, and/or outright annoying.
In one case, an intern at work friended me, which meant I could see all of her beach bikini photos from the prior weekend. Now that was TMI and warranted immediate unfriending... haven't friended anyone who is a current colleague ever since.
It remains to be seen how many people are actually unfriended as a result of this.