DroidWall - Android Firewall is a front-end application for the powerful iptables Linux firewall. It allows you to restrict which applications are permitted to access your data networks.
This is the perfect solution if you don't have an unlimited data plan, or just wants to see your battery lasting longer
3G Watchdog. Guarding you against costly Internet overages. 3G Watchdog data counter monitors your Mobile Internet (3G/Edge/GPRS) data usage, shows a status icon (green/orange/red) in the notif bar and a detailed report page. Widget (2 sizes)
5 VPN - Starting a VPN connection on Android is not very convenient. Normally it requires 7 clicks and writing a password. If you want to avoid writing the password, you can copy it to the clipboard, and then paste it, for a total of 11 clicks. With this application however, it can be done in 5 fast clicks and no password
Autoproxy Lite - The most complete proxier for Android. Autoproxy allows you to use Market, Gmail, maps or surf the web even behind the proxy from your home/school/office.
It works by creating a transparent/intercepting proxier running on your phone that redirects web traffic to your proxy
APNdroid - Toggle that prevents your phone from connecting to internet over 3G/EDGE/GPRS. This application modifies APN names and types by adding 'apndroid' suffix to them (you can edit them anytime in your phone's Settings).
NOTE: Uninstall with enabled internet access! Otherwise you will be offline, needing to change APNs manually.
What's New in 2.1.3 / 2
Network Widget - Simple widget to know active network information and to switch WiFi on/off.
Is your device on WiFi or data plan mode?
What is current IP address?
Click on network name to show preferences.
Click on icon to toggle ON/OFF WiFi.
Note: this is a widget, you HAVE to add it to your home screen
FTP server - is a useful utility to manage and share the files between computer and smartphone through FTP client. Personal computer and mobile device must be connected to the same Wi Fi net