Paint.NET (free software) has an effect that improves sharpness and works quite well, but it all depends on the originals... There's no magic software :) (in Paint.NET: Effects, Photo, Enhance Sharpness)
Unfortunately, it's impossible: http://www.commentcamarche.net/faq/sujet 3186 myths about getting a sharp image from a blurry photo (unless maybe in NCIS or CSI).