On most of the GSM mobile networks now, it is becoming standard practice that when you load airtime, you are rewarded with some complimentary data for internet access. Some networks do even better and add free airtime and SMS.
On my own primary network, the amount of free data you are rewarded with is proportional to the airtime that you load. As such, the more you spend, the more free data you get. This is a good thing, of course. A lot of things sure have changed since the early days of mobile internet connections at N50 per minute.
Does your network give you any free internet data when you recharge? Do you find such a freebie useful?