Git Sketch Plugin - Version control for designers
NimbleText - NimbleText is a text manipulation and code generation tool available online or as a free download.
Select Similar Layers - Sketch plugin to select layers with the same attributes
WordCounter.net - Count words, sentences, paragraphs etc.
Floverview - Hybrid mapping for flow overviews
Heytools - JavaScript tools, AJAX tools and some fully server side tools.