Is it possible to launch an application from a browser? I am not talking about opening a file from a browser (like open a PDF with Adobe Reader), but rather opening a new (blank) instance of an application that is installed on the user's machine.
Hypothetical situation: User browses a website that lists computers that can be managed via RDP. He clicks on a link to 192.168.1.10, that link opens Microsoft RDP client (mstsc.exe) with that ip address already filled out.
I am talking strictly about Windows universe.
Is that thing even doable outside of ActiveX and IE?
Is it wise to attempt this in IE with ActiveX?
You can't really "launch an application" in the true sense. You can as you indicated ask the user to open a document (ie a PDF) and windows will attempt to use the default app for that file type. Many applications have a way to do this.
For example you can save RDP connections as a .rdp file. Putting a link on your site to something like this should allow the user to launch right into an RDP session:
<a href="MyServer1.rdp">Server 1</a>