Thanks for the tips so far everyone, you've posted some great ideas.
Just to clarify I would like to be able to go to a website from home and see the temperatures of my tanks. Read/write access would be even better so I could adjust values if needed. AdvancedHMI and PeakHMI both looks like they would work but how do I access them remotely. I'm sure I could use TeamViewer or Remote Desktop but I would prefer a web based interface to keep it simple.
I've used Ignition in the past and it is as simple as typing the servers address in your location bar and launching the Java based client, but it comes with a $10,000 price tag.