Inbox Creature - A super cute virtual pet, delivered right to your inbox.
Penny - Penny is a personal finance app that takes the pain out of keeping track of your finances.
Mailtrack.io - The best email tracking solution I've found. Free
Digit - SMS bot that monitors your bank account & saves you money
Tamagotchi Pix - The latest Tamagotchi now with a camera
Spendee - See where your money goes