Halo has a lot of titles for a 10 year old franchise, but I wouldn't call it milked. The game are good enough and the changes are significant enough that the series is still worth it and not just year after year minor improvements for full price.
Things that are milked:
- Guitar Hero franchise
- Naruto
- Really most any music rythem game (the whole Hero and Band franchise)
- The Sims
- Call of Duty (even though MW2 is great)
- Final Fantasy
- Raving Rabbids
- Madden/NCAA (I use to defend these, but the past few years haven't been that significant)
- Starcraft II will be milked to all Hell
Those are the ones I can think of off the top of my head








