I've thought for a while now that a neat thing to do with all those Achivement points would be to spend it on player housing.
Consider that player housing is the only thing WoW has not implemented that other games have.
I really enjoyed how DOAC did their player housing. Aside from guild halls, but player houses were customizable and could hold things like trophies from kills.
Granted, there would have to be a special zone for all this in a WoW setting, and maybe it doesn't go with the lore all so much.
But, imagine your titles, raid achievements like killing Ony, or pvp accomplishments. Others could see what you have done in a more physical way than looking up a list on the armory.
An argument could be made that it would be a time sink, but achievements already are time sinks. PvP in WoW in a sense is a time sink.
However, people like to show off what they have done and others like to see what their friends and competetors have accomplished.
Now, I don't think points should be spent in order to buy things like housing, but all the housing things (special hearths, ports, banks, trophies) could be unlocked as you gain more points, no matter how you gain them.
Embrace the time sinks and let us show off what we have done in the game with pride.