What tool should I add next?

I'm getting FileMagicPro ready for launch on July 30th. It's a set of 30+ free browser-based tools (PDF converter, compressor, OCR, background remover, and a few calculators) — everything runs locally, no uploads.

While I finish up, I'd love to hear from you: what's a file/document task you find annoying that you wish had a free, no-signup tool for? I'm always looking for the next tool to build.