Anyone know any good tutorials or articles about the basics of developing web apps that run clientside?

I need a web app that runs client-side so that it has access to the user's scanner. I think activeX would be the obvious choice for this but I don't really know much about activeX and from what I can tell Microsoft is trying to get away from ActiveX so to write activeX I would have to use VB6. That could be an option but I am concerned with how well it would work with .net as I need the control to interact or atleast send data to our serverside web app that is in asp.net/vb.net.

I had a demo project I downloaded from LeadTools (LeadTools is the library I plan on using for TWAIN support and image processing) that was very similar to what i was looking for. The project had a UserControl (it was in C#) that created a DLL which was embedded in an html page. I was able to setup IIS to serve this page and It worked perfectly, it was even able to access a scanner on my machine. However if I tried to access the page from another computer on the local network (or even from my own computer using my local ip address instead of "http://localhost...") IIS would serve the webpage but the object would just be a plain empty white box. If I could get this dll to download and run on other machines beside the one hosting it than I would be able to easily use this as a guide and get what I need out of it.

Sorry for such a long and needy post, I've spent hours upon hours of time searching for a solid explanation of how to do this and have had very little progress.

Thanks in advance for any help or ideas you can provide