In what kinda public network exactly, and how do you connect to it? If you use a secure connection (WPA2 or similar, WEP is easily hackable), you usually have nothing to worry about - usually only things that are recorded are things such as the sites you've been visiting (i.e. not the actual content or the date you've sent them), and even these are accessible only by network admins. If you're connected through an open connection (one that doesn't require a password, that is), you have more to worry about - only send data over secure (encrypted) connection if possible.