help with adding thumbnails to posts ..

with the help of embedly, websnapr or shrinktheweb. or similar provider, i want to have thumbnails to appear next to posts. i have a [login to view URL] light rip off script from Hotaru CMS, that i have customized a bit. it works a bit like pligg, where you download a script and then add plugins for nearly every function that you want to have on the site. i was thinking that a gravatar or post images plugin could be modified to work with one of the above mentioned plugins. i have posted an example of how i want it to look.. users already have the function to add a thumbnail to their post, but it is a process of pasting an url, selecting thumbnail ( if the link holds more than one ) and cropping. i just want the function to grab any image at the end of links, not giving the user a possibility to crop and edit, or to just make thumbnail automatically if url is directly to an image. hope i made myself clear, and that someone can help me with this problem ? thanks