Checklist Design - The best UI and UX practices for production ready design.
UXsniff - Track user behavior on your website and improve conversions with UXsniff: the user experience watchdog that looks out for you.
uEye - uEye is free, fun, and an interactive way to learn UI design.
Uxcel - The easiest way to learn UX/UI design
UI Checklist by Shift Nudge - After I finished all of the Shift Nudge lessons, I went back through a wrote a checklist of 101 items you can use to self-critique your designs.
Interface Design Mastery - 200+ pages of actionable tips and tricks for your everyday design decisions.