http://www.mixedinkey.com/
The heart of harmonic mixing. Use this to recognize the key of the Track. There are some tools on the market that does the same, but Mixed in Key stands out as the best.
Ableton is a great tool and one of it's coolest features is warping. Warping can be used to fix tracks that are not recorded on click. See how in this video.
http://www.itunes.com/
Itunes
Traktor has a good Traktor integration and this can easily be the best place to manage your music for Traktor. Atleast for the ones of you who use Macs.
Winamp has alot of cool features like audio recognition and tag editing.
Tag & Rename
Gets your collections in order, get full info on your tracks and import cover art from amazon+++.Great for editing multiple tracks at once.
Traktor Addons:
Traktor Tools,
Trainspotter,
Advance playlist editor,
Rapid Evolution 2,
Twitter DJ,
Traktor Pro Launcher,
TSI-view & Print
Info will be updated. ;)