I own a HTC Desire HD and I find it extremely handy when it comes to banking online or checking out my social networks.
This is where SSH Tunnel comes in. SSH Tunnel allows you to connect to a secure SSH (secure shell) server and pipe all your internet traffic through an encrypted tunnel. Some of the main downfalls of SSH Tunnel are that you need a rooted Android phone, access to a SSH server and a little bit of technical knowledge.
If you are interested in more leave a comment and I can discuss it in more detail.