Makerlog - Makerlog is the dead-simple task log that helps you stay productive and ship faster.
Koalendar - Free Online Appointment Scheduling Software
WIP.co - Work in progress. We are a community of makers who help each other ship product.
Square Appointments - Add an online booking link. Easily embed the customizable widget directly on your website. Any changes to your online scheduling, prices, or services update automatically.
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
With You and Me - Create a page that accepts appointments easily:1.