The best devtool ever? Or the best devtool ever?  You decide; I present the fantabulous Terminals.

Once you've lived with it, you can't live without it.

It addresses several shortcomings with the default RDP/Terminal Services client in Windows, namely:

• Lack of support for tabbed viewing of connections (who likes to have 5 different Remote Desktop windows open?).  Terminals supports tabbed browsing of Remote Desktop connections.
• The need to save one .rdp file for each connection...what a pain in the butt!  Terminals supports saving of the client connection information for you automatically.  Not only that, it can add configured connections to a toolbar for easy access (instead of hunting down saved files).
• Lack of tools for connectivity testing.  With the default MSTSC, it requires you to jump to the command line to run ping and other utilities when testing for connectivity.  Terminals has it built in!  Awesome.
• No support for connection groups.  Quite often, when working with VMs or remote machines during development, you have to access the same group of machines at the same time (for example, a server and a client).  With the default MSTSC, you have to manually start the two connections or write a batch file to open them at the same time.  Terminals has a grouping feature which allows you to initiate grouped connections automatically.

During development, even with VMWare running locally, I prefer to use a terminal services connection instead since it's way more responsive to user input.

Terminals is definitely awesome.  There are still a few issues like auto-scaling and auto-resizing which don't work quite right yet, but otherwise, it is fantastic.  Note that it also doesn't support connecting disks and printers and what not (maybe next release).