UI Garage - Specific mobile and web design patterns for your inspiration
Waitlist API - Quick and easy waitlist with built in referral.
Muzli - UI/UX and Design Inspiration Chrome Extension
LaunchList - Create waitlist with referral for your product launch
Design Hunt - Curated design inspiration for everyone
Waitlisty.io - Build excitement for your product by embedding a simple form into your website. Signups will receive a referral code to share with their friends. The more codes they share, the more they climb your waitlist.