Track your balance/limits/credits/data over USSD (Android 4.1+) or SMS requests and show changes in nice widget. Background requests supported after call, on schedule etc. If you use code like *100# for getting your balance, you can easily configure piBalance to use this code.

Pro features: full statistics for day/week/month/year!

And the following mobile operators supported out of the box:
Australia: Optus, Lebara
Belgium: Base (KPN Orange)
Bosnia and Herzegovina: BH Telecom
Bolivia: Tigo
Brasil: VIVO, TIM
China: China mobile, China Unicom
Costa Rica: Kolbi I.C.E., Movistar
Finland: DNA Finland
France: Free
Greece: Vodafone
India: Vodafone IN, TATA DOCOMO, Aircell, Reliance, CellOne
Indonesia: INDOSAT
Ireland: Vodafone IE
Kazakhstan: Tele2
Kyrgyzstan: Megacom, Beeline
Latvia: BITE
Malta: Vodafone
Nigeria: Nigeria Communications (MTN)
Namibia: MTC
New Zealand: Vodafone
Pakistan: Ufone (Pak Telecom Mobile)
Poland: Orange
Portugal: Optimus (Sonaecom)
Philippines: GLOBE
Romania: Orange (MobilRom)
Russia: MTS, Megafon, Tele2, Beeline, SCS, UTEL, Smarts, BaykalWestCom, Rostelecom
South Africa: Vodacom, Cell-C, 8.ta
Serbia: TElenor
Switzerland: Swisscom
Sri Lanka: Dialog
Tajikistan: MegaFon
Thailand: Dtac
Turkey: AVEA
Turkmenistan: CELL, MTS
UK: T-mobile, O2, Vodafone
Ukraine: Life:), Kyivstar, MTS, Beeline, Utel
Uzbekistan: Beeline

kw: balance, limits, ussd, widget, check balance