The LabProTM interface boxes by Vernier Inc.,
allow one to gather experimental data in real time.
One can measure temperature, voltage, current, distance and velocity, force,
etc. using a variety of attached probes.
Typically, a LabProTM interface is connected to
your computer via a serial cable, and a server program (e.g.
remserial) is running,
exposing this serial line as a tcp/ip port (defaults to port 23000) to which the browser can connect through the web.
If this is not the case, try the "demo" mode, using channel 1 or D1.