Awhile back, someone was talking about an app that upsamples video stills. I can't seem to find that thread. Anybody remember what that app was called?
You are probably thinking about http://www.topazlabs.com/topazlabs/03products/topaz_moment/Topaz Moment[/link]. It works quite well though I haven't used it nearly as much since moving to HDV (because the HDV frames are already pretty high resolution).