If you'll forgive the self-promotion, you might like to check out my web app, Testpad (https://ontestpad.com), as a lightweight tool for organising manual testing. It's basically structured checklists rather than formal test case management, and has been doing well at agencies both big and small. Because it's lightweight and flexible (think cross between Excel, Notepad and OmniOutliner) you can start out as simple as you like and iterate the complexity as and when it's appropriate.
And to answer your question: I am of course using it to test itself! Plus some selenium for basic automation, but without going overboard as the app is very javascript-heavy and interactive, which limits how much can be usefully/cost-effectively achieved with automation.