What problem is REALLY bugging you? 
roel_v: How ebooks that are distributed in pdf are so hard to read on small screens, and the lack of properly working pdf->reflowable format (epub) tools. This is a hard problem and I'd pay for a 80% solution. It would have to recognize and properly fix/insert chapter titles, initial caps, tables of content, other leader/footer material, ... It would have to properly insert images in a sensible spot yet remove background images. Also it needs to properly recognize and format paragraphs. Columns would be nice but those are in the 20% I can live without.