I use a simple solution using Amazon AWS EC2 service. I just start a prepared EC2 image on cheapest instance. This image contains installed Shell-in-a-box (Web based AJAX terminal emulator) and usage manual.
Shell In A Box implements a web server that can export arbitrary command line tools to a web based terminal emulator. For details see its homepage.
When I don't need the server anymore I just terminate it. The cost is several cents ($0.006/hour for Spot request server).
I you would like to try it the image name is ami-c73ef2ae (currently available only for US East - Northern Virginia).
WebConsole tutorial running on port 80
WebConsole shell running on port 443