Nuance's T9 Nav concept is simple yet brilliant that I wonder why no one has seized on it before (ok, there has been but the execution and integration here seems to be better). The plug-in allows you to easily search almost anything on your phone from the standby screen simply by typing in the first few letters using a T9 compatible numerical keypad. It works similarly to the phone app (Smart Dial) on Windows Mobile, except that it isn't limited to contact entries.
Once activated the program will first index the content of your phone. This includes contact details, settings, music, images, bookmarks, applications, calendar entries and keywords. It took about 10 seconds for the application to index my E51, but your mileage may vary depending on how much junk is installed. You can also set the program to auto start-up whenever you boot your device. A simple tutorial is also provided with the installer though the application is so easy to use I did not once refer to it.
Using T9 Nav is child's play. On the home screen (or Active Standby as Nokia calls it), start typing on the keypad as you would normally do. For example keying in 2-7-4-4-4-8-6-6 will type out 'Brighton'. Doing so here list all the entries on my phone that contains the keyword 'Brighton'. In most cases all I had to do is type first couple of letters for it to start sorting out the entries properly. For example typing 7-2-4 allows me to switch to pager profile, check my schedule (calendar), launch the National Rail's website or call Aishwarya Rai . Results become more refined as you press more keys.
Right now T9 Nav is still limited to indexing certain portions of your phone. I do wish that once it is ready to be released Nuance would implement some sort of filter to the end-user, giving us a choice to decide what we want indexed or otherwise. Another wish I do have is for Nuance to give us the ability to include SMS/e-mail entries, similar to Windows Mobile 6's Smart Filter. However despite these limitations, the convenience of T9 Nav has already won me over and I can't recommend this enough to people with compatible mobiles. I can always fall back to the built-in Nokia Search for a more thorough (but much slower) search.
T9 Nav is scheduled to be released soon as a commercial software. The public beta is available for download here (for Series 60 3rd Edition). A similar program Qix by the developers of Decuma is also available.