I have the mobile UPS, FedEx, and USPS websites bookmarked on my BlackBerry but a friend of mind introduced me to PackageTrackr today. It is a sweet website which also has a mobile friendly view that allows you to track your packages shipped on practically every carrier I can think of.
PackageTrackr has all the regular carriers covered in the US including others like Canadian Post along with 15 or some others I cannot recognize like CEVA, Aramex, Hongkong Post, Parcelforce, and many more. It will usually autodetect the carriers.
PackageTrackr does not have a BlackBerry app (yet?) but they do have a nice mobile version of their desktop site www.packagetrackr.com.
You can get to the mobile site at www.packagetrackr.com/m/ or go to the iPhone optimized version which looks beautiful on my Torch at www.packagetrackr.com/iphone/. Let us know what you use to track packages on your BlackBerry? I used to use Viigo but that is a lost cause since they have yet to support OS 6.