Trello is not just a to-do manager. With this app, you can organize any project into cards, which can be used as a private tracker of your progress, or shared with friends and colleagues that you're working with. To top it off, it all comes in an attractive package with cloud syncing.
Everything in Trello is grouped into boards, which should be treated as separate projects. The cards are individual aspects of each project board. You might want to add cards with photos, notes on who is working on various items, or checklists of individual to-dos. You can imagine Trello as a sort of virtual whiteboard for keeping track of your ideas.