http://wow-pro.com/ This is a free leveling guide (it actually contains guides for near all levels but of interest is guides for the new level 80+ zones) which has been updated lately
using tomtom this can be quite useful!
There are a lot of "paid" addon guides online (though i think that violates the terms of the agreement as i think any UI addon is supposed to be non commercial) but its nice to see one thats free with no fuss.
Also Carbonite a nice overall UI addon that adds a great minimap/full map to the game http://www.carboniteaddon.com/ has been updated to include the new Shattering maps (which include the zone maps for Cataclysm) so both together would make great guides/tools in game :-) fun!
Hint: You really don't need those kind of addons in the new and revamped zones. Everything's pretty much selfexplanatory and you'll get send from questhub to questhub, after you're done at one place.
I just go without addons,only using my PvP ones (for arena) and quest helper.I like the wow UI atm since it has taken numerous positive things from many addons,so at the moment I think I am ok