I'm sure there are other posts about this elsewhere, but I figured as USCC customers (since we're all here for the Mesmerize) would really enjoy this app.
I found it while reading the articles here at Phandroid.com and really loved the app they recommended so I am here to recommend it to you all, as well.
The application is called 3G Watchdog. Here
is the link to it in the Android Market.
So what does 3G Watchdog do? Well as USCC customers, we all know that we have a limit to our data usage. Depending on your tier, you may have a lot of data, or a little, or a lottle. Whatever the case may be, with this app, you are able to enter in your billing cycle dates to help monitor more accurately how much data you use. The first date should be the day you pay your bill (ending cycle day) and the second should be the start of your billing cycle (the day after your bill is paid for the month).
After those dates are entered, you're pretty much done! You can adjust the settings to how you'd like as far as how often the program refreshes the counter.
The app displays your usage in different formats depending on your taste. For me, I chose data display + percentages. Now let me say that before I had this app, I limited myself to how much data I used when not on WiFi. I would wait til I got home to download apps, listen to music, etc. Now, after downloading the 3G Watchdog, I've realized that it takes a LOT to hit the 5GB data mark. I'm about 75% of the way through my current billing cycle and I've only used up 5% of my 5GB data plan using apps such as Pandora, YouTube, Netflix, Browsers, etc.
If you purchase the pro version, it can work in unison with JuiceDefender (another app that disables your 3G when your phone is not in use) and as your data reaches the higher percetile (60-99%) it can activate JuiceDefender and disable your 3G until the next billing period.
Personally, this is a must have app for me as I love listening to Pandora and watching movies on my phone.
Hope this helps in some data endeavours!