Does anyone know any cydia app/tweak that allows you to not only see the battery percentage in the status bar but to also see how many minutes you have left in your battery, tia.
Minutes left would only be a very very rough approximation dependent on what else you were doing with your phone. If you use it over wifi or 3g or use bluetooth or standby, it all changes how quickly the battery is consumed and no app would reliably be able to tell you how many minutes you have remaining.
I think I've seen an app or two in the Apple app store that does this kinda thing. If I recall, the app offered you an approx. # of minutes remaining for video, music, and talk time, but like 9erfan said, an app could only offer a guesstimate.