I once requested this addon on the Curse gaming forums, and a fellow by the name of Kaluriel picked it up as he was already working on such a thing anyways. However, his released version hasn't done my idea justice :/
I wanted an in-game Talent Calculator. Something very similar to the various calculators you can find on quite a few websites. With a database to display all of these talents in-game, this addon would allow you to view your talents and plan the path you wish to take with your talents in advance.
Not only this, but it would be handy to have the information available at the click of a button. Part of being a great asset to your party is knowing your character's role in that party. By understanding everyone else's role in your party it is much easier to do that and knowing the key talents in other classes trees can be very beneficial.
Now I'm not saying that I'm not thankful for Kaluriel's work here. I'm just stating that I believe he's building this mod to look/act in a manner that I wasn't looking for. While I'm sure many would enjoy his addon, my thirst for such an addon has remained unquinched.
I do like his attempts at creating his addon "Kalented", however I find it quite useless in comparison to any other talent calculator..
The Websites provide me with too many features, and are too much more visually gratifying for me to bother with an addon that barely does more than the already implemented talent frame. While I am aware that he intends on adding a database himself, I still find his addon visually displeasing and featureless. Also, I feel rather confident that if it were done over with priority on efficient and clean code such as the ace community stands for, the addon would be more to my liking.