Pageonce is known for their personal assistant app for BlackBerry that gives you access to your online account information for many sites. Their personal assistant app has a free and premium $9.99 version that gives you access to more as you can see in this chart. They just released a subset of their application called Cell Minute Tracker just for tracking cellphone minutes that has both a free and paid version. The free version is kind of pointless since you can do the same things with the full free version but the paid version is only $2.99 which gives you access to family plans, more accounts, and no advertisements. (comparison chart)
I signed up for the regular version of Pageonce awhile back and it took forever to get off their annoying mailing list. I found the mobile sites for American Express and Chase offered me more information and more functionality so I gave up on the idea. Still it is a pretty nice feature to collect all this information so I do it completely free with Yodlee MoneyCenter which has both a desktop and mobile website and tons more account options.
If you are looking for a simple way to track your cellphone minutes on most US and Canadian carriers check out Pageonce Minute Tracker (free|Pro) or Pageonce Personal Assistant (free|Pro) . Otherwise let me know what you do to keep on top of your cellphone usage.