A basket full of Awesome
Not that I don't sympathize. Keeping any significant number of PCs free of malware is difficult enough when your user base can't install software. I just don't think the jack-booted thug approach serves the interests of employees or the company very well.
So, if you are unfortunate enough to live or work someplace that blocks SSH, and/or you cannot install an SSH client, there is a solution. If you have a server somewhere, just install AjaxTerm. Then you can log into a cute little AJAX terminal using an ordinary web browser (don't forget to use SSL). The terminal itself is surprisingly snappy. It is even snappier over SSL. It's not quite as interactive as a local xterm, but it's quite usable. It's a bit like using a 2400 baud modem.
It's dead-simple to install, too.