If you're the 'collector, achiever' type then Skyshards & Lorebooks are great and help you rack up your skill points. I love Craftstore as its an outstanding piece of work and as an avid lovers of alts, I also use Do I Need It For Alt's, Sous Chef and Research Assistant.

Finally I use AUI (mostly for the map), Ravalox Quest Tracker, Harvens All Experience Bars (I love to see progress) and Harven's Potion Alert which helps when the action gets frantic