I am always on the look out for cheap internet usuage. So i wanted a sim that will give me unlimited internet even while roaming and has to be a prepaid sim. There are not many option out there. There are some unlimited options, but the have a fair use policy, which means its not unlimited. So after my exhausting search here is the winner.Aircel has the best unlimited gprs plan out there, its 97 Rs per month. This is truly unlimited, no fair use policy bull shit here. I have used nearly 5 Gb for this month alone and its still working. I have been using this service for the past 1 year. I always use more than 5 Gb per month. The best part is it even works unlimited while roaming. This is the best option for a data sim especially if you are in the south of India.I wouldn’t recommend it as your phone sim, because they have very little coverage. But for you data and internet need this is it. It even works as a usb data card sim, if you use it with bsnl 3g usb modem. Its got good speed too, i got 80 kbps with the data card.Now others are offering unlimited plans, but aircel been doing that for the past one year.By they way if you want to know what i use the 5 Gb per month for. Its mostly for podcasts, i use listen app on my HTC hero. If you are using android phones with auto sync turned on, it will suck up quite a bit of data.