See this question here for your command line options. Basically, you've got WinRS/WinRM, PowerShell Remoting and PSexec and the other SysInternals Suite utilities. You can also install SSH, or even telnet on a Windows server, and connect to that, once it's installed.
Additionally, your tools in the Administrative Tools folder will let you connect to remote machines (or at least) try, so that's an option. (Mostly your MMC snap-ins, but even some of the natively included standalone exes, like
regedit, have this functionality.)
You also should have some form of Out-of-Band management interface/virtual console on your server (such as HP's iLO or Dell's iDRAC), and if not...well, learn from this and get one on your next server.
Finally, there are any number of third party tools that will often allow you to access a server remotely, install themselves, and then set up a screen share based on VNC (or similar). Dameware and IntelliAdmin come to mind immediately, but they're just two of many.