Speedtest.net has developed a free iPhone app that measures the speed of a web connection using the first access point, which could be your Wi-Fi or 3G connection. The app will measure the net connection upload, download and Ping speeds on your device. Once complete, the results will be displayed onscreen. Alternatively, it'll let you an access results from previous tests to help you work out when it may be preferable to use one type of connection over the other.
iDataSpy lets you track your cellular (3G/EDGE/GPRS) and WiFi data. You can even view the results in a bar graph.
This is a great app that that takes the data you receive on your handset when surfing the web and pass its through the firm's compression service, decreasing the size of the data and subsequently ensuring you pay less for data downloads.
3G Mapper Lite
With this app you can create your own 3G coverage map. Dots (which are added automatically) on the map show you where you do and don't have a data signal. You can even combine all your different logs into one large map and share with other.
This free app lets you search for the nearest Wi-Fi hotspot from 55,000 locations in 144 countries across the world. You can even get directions to the hotspot without leaving the app.