HelloSign looks great! DocuSign is another good alternative that a lot of bigger companies use, but the UI isn't nearly as good.
IFTTT is pretty good, but Zapier is incredible for doing anything related to business. You do have to pay for it to get the most functionality (fast updates, more 'zaps', etc), but the free version works pretty well also. I use it mainly to sync all of the different apps I use together, and it's been a lifesaver on more than one occasion.
My best lifesavers have always been apps that take potential distractions away. I use iA Writer to do all my writing on iOS or my Macbook and a combination of Self Control and RescueTime to keep myself on track and focused.
Also if you're trying to learn something, I highly recommend using spaced-repetition flashcards. Anki (ankisrs.net) is a good cross-platform solution.
Oh yeah, and also #GiveMeSETT