I've just discovered another useful 'app' for Android phones for people doing genealogical reasearch. This free app is 'Google Cloud Print', and it enables an Android smart phone to print to a printer connected to your home PC, and the Android phone does not have to have wi-fi access.
What is required at the PC end is that the PC must be switched on (of course), and must be running the Google Chrome browser, and you must be registered as a Google user (that's free).
The phone sends the image for printing via 3G to Google's cloud server, and from there it is sent via the internet to your PC, and then automatically to the default printer attached to your PC.
Google Cloud Print can also be used to print documents on other people's printers from a PC. Printers are now appearing on the market that are 'cloud ready', which means that they don't need to be connected to a PC to print from Google Cloud.
Another useful Android app is Dropbox, which we've mentioned before, so I won't elaborate.