A very simple network connection testing tool.
It simply sends a TCP packet on the specified port to check if connectivity can be established. Despite it's simplicity, the fact that it can be replaced by a single powershell cmdlet, and it's limited functionality, this tool has become one of my most used tools. I suggest placing the .exe file somewhere in your windows path. For example you can just place it in c:\windows, or better yet, add a custom c:\tools folder to your path.
Note: Current Issues
Feel free to download the compiled version here: