I've fallen in love with TimeTrack. Amazing feature set for free. It started as an app if you can believe that. Imagine managing your time on your iPHone? I was skeptical but tried it and am so glad I did.
I can't believe how easy it is to use and create invoices. All on my iPhone 6+. The best part for me is it being on my phone, I can catch up on my time tracking duties while I'm waiting in line at the pharmacy or the bank. That's the secret sauce: Accessibility combined with powerful features and a great UX.
Since I started using it, he's released a cloud version so you can install it and use it everywhere you are.
A close second is Zoho's expense tracking web app, very powerful. Harvest was also great though it is a paid subscription model.
I use Calendly for scheduling and love it. For productivity, there's a great Pomodoro based app called FocusBooster.
Also, check out RescueTime if you want to analyze your computer habits and find out if there is time your spending that you should spend on more productive tasks.