I never thought I'd hear myself say this, but I really like the new achievement system introduced into WoW with patch 3.0.2. I've never been one to care much for titles or non-useful items gained by world events or the like. Yet I have found myself actively working toward achievements these past few weeks. Lately I've spend an inordinate time leveling up all the old faction reps, and ended up having to spend about 1k gold on runecloth yesterday to finish off Gnomeregon rep. But I finally got my Diplomat title, and I've now purchased all the non-epic and epic land mounts for the old factions (minus Gnomeregon since Dranaei can't ride chickens!!) and purchased all the non-epic and epic flying mounts. So I wake up this morning with 33 mounts in total (also have the AV Battle Ram) and have started my Kureni grind. Luckily that one doesn't take too much time, and I've also recently started my Nethwerwing and Skyguard rep grinds. With some luck, I should have my new Albino Drake flying mount in the next couple weeks.
If I could add just one thing to the achievement system though, I'd really like to see some additional rewards for various achievements added in. As well as other rewards that can be purchased with achievement points.