Photoshop would be one program. But, there is a free program called Ifranview that will let you increase the resolution of jpg files.
As for video, I don't think there is anything that will make poor bit rate movies look better. You can find programs that will increase the resolution, but that won't make it look much better. For instance, if the video has artifacting because of the low bit rate, those artifacts will remain on the "up-converted" version too.