GitHub Rebase #39 highlights several innovative projects, beginning with rhodes, an open framework for mobile app development that simplifies the process of writing apps for multiple platforms using Ruby, offering features like Rails-inspired templates and device capability exposure. The post also introduces octosquashes, an experimental Ruby-based visualization of GitHub's public timeline, and LastHistory, an OSX tool that visualizes a user's Last.fm music history in unique ways, integrating photos and calendar data. Furthermore, it showcases phake, a PHP-based task automation tool similar to make/rake, which allows developers to manage tasks with dependencies and hooks. Additionally, the html-minifier project focuses on web optimization by reducing HTML page bloat, and hector, a Java client for Cassandra, provides a high-level interface with features like automatic failover and load balancing for improved database interaction.