Ask HN: Want to create $5 Excel add-in for charity, help with ideas

Hi, I want to create a $5 Excel Add-In that will support an Australian charity that supports people who care for disabled people. It will be totally trustware, in that people can download it and if they want to continue using it they should pay $5, which will be donated 100% to the charity (my business will cover all costs), but I wont have copy protection. I'm looking for better ideas. Currently my best ideas are : An Mp3 library. - When the open the add in it can scan your hard disks, locate and list all audio files. - You can save the file information to a worksheet - Possibly load metadata on the files from a free web api (does a free music metadat api exist ?) A DVD library. - Manually enter DVD information and then record whether you've leant the DVD to someone. - Would be cool to allow bar code images to be used but I doubt there are free lookup services to get the DVD information from the barcode There has to be better ideas than these :) I think the idea should have relatively broad appeal, although I guess it's a big world and even a specialist tool could do well. I am going to stick to making it an Excel Add-In because I think that's a pretty big market and it's something I have experience with. Cheers Sam