Finding a good remote desktop client can be tough. A lot of companies relent and just use some variant of VNC. But, even VNC has its drawbacks considering it will crash with too many open connections.
Designed as a full replacement for the Terminal Services client (mstsc.exe), Terminals provides a shell for the Terminal Services ActiveX Client (mstscax.dll), but does so in a way to improve the entire experience.
Using a tabbed interface, you can open multiple connections and then switch between them without losing existing connections.
Terminals supports all the major server protocols including RDP, VNC, VMRC, SSH, Citrix, Telnet, and RAS.
The application is fully customizable and feature rich, including things like Wake On Lan, port scanning, screen capture, ping and tracert, and others.
Try it here: Terminals on CodePlex