There are lots of installed applications which connect to Internet along with the browsers, chat and email clients, not all these connections are desirable all the time. Windows 7 Firewall Control is a freeware tool (previously available on Windows Vista) for Windows 7 which can protects your application from undesirable network incoming and outgoing activity, controls applications internet access and allows you to control personal information leakage via controlling application network traffic.
When you run the application, it blocks all outgoing connections and you need to specify the ones which needs to have access to outgoing and incoming traffic. You can specify if you want to provide access to incoming as well as outgoing traffic for each application. You can either disable all or enable all or selectively provide access.
It notifies you every time a new application tries to access the internet. The free version has less features, but still provides good safety to PCs. It is supported on Windows 7, Vista, Vista Service Pack 1 (SP1) and Vista Service Pack 2 (SP2).