Keeping track of everything I do/need to do. I've tried a lot of web apps from every major and minor player out there, but nothing works for me. I'm about to start to write my own CRM/TODO/PM app because its the only way I will get what I need. I might even open source it if it doesn't end up too "hacky".
A Todo app, with a timetracker that opens up on the mac status bar would be perfect... I have faced the same problem for a long time, let me know if you are working this app, I would like to contribute