Disclosure: I'm one of the founders of Tiempo
Most people default to pen, paper, or Excel. But, it quickly becomes more hassle than its worth. And, if the hours you track need to be sent to a finance team or an accountant, it gets even more complicated. That's why we created Tiempo.
Tiempo is a new time tracking app that aims to be the fastest way to track time. It works on the web and has apps for both iOS and Android. We even use it ourselves to track developers we have contracting for us.
Plus, you can have unlimited customers, even on our free tier (Harvest limits you to 4).
Check it out at https://track.tiempoapp.com/signup or see our site at http://www.tiempoapp.com.
The Tiempo team is made of former Intuit employees that have spent their careers focused on building software for small businesses.
We'd love any feedback the HN community has!