Is there a tool in the WebADF that will let me draw a straight line and calculate the distance between the two points.
There was a 'Measure' tool that should do what your looking for. But keep in mind that the ADFs are being depricated and don't have a huge amount of life to them.
You can take a look at the code-gallery, there is a lot there you can start off playing with.
But keep in mind that most of this will not work fully in ArcGIS 10.1, since the core API and libraries are going through some major shifts.