If you just want to add an URL to a jpeg that is refreshed periodically (travel cam, web cam) then you can select the "Generic URL" camera type in the "Add Camera" screen accessible from the "Manage Cameras" screen. Note that this works with mjpeg streams as well.
With version v2.8.0, you can now use the built-in web browser to add any image (travel cam, web cam) to IP Cam Viewer simply by:
1. use the browser to navigate to any page
2. long pressing on an image
3. select "View Image" from the popup dialog
4. select "Add/Edit Camera".
5. this will bring up to the "Add Camera" screen with the camera type and url automatically populated.
6. Press Test then Save.
Oh, and don't forget about the home screen widgets for your cameras added in v2.7.x