Some of my highlights (checkout my Github repositories):

• Temperature-Machine - Homebrew data logger to record and chart temperatures
• Scala for Java Developers - Source code companion to my book
• Radiate - Scala build monitor for TeamCity that will run as a screensaver
• Unicorn-HAT - Java library to drive WS2812B LEDs like Pimoroni’s Unicorn
• Paste.ly - IntelliJ plugin to simulate typing, useful for screen casts and demos

Some of my open source projects which had some traction:

• tempus-fugit - Java library focused around concurrency and testing
• simple-http - An improved Java API over the Apache HC HTTP library. Read a little about it.
• simple-excel - An improved Java API over the Apache POI project. Generate and test spreadsheets. Read a little about it.

Some of my other projects and contributions, mostly inactive now:

• JMock - Mocking
• Window Licker - GUI Testing framework; a patch to support SWT
• XCordion - Acceptance testing framework, forked from Concordion
• concordion-ant-task - an Ant task to collect Concordion specs in a single HTML overview
• Jedi - Functional Library for Java, added set compliment filter JEDI-21
• SWTBot - SWT GUI testing framework
• Nebula - SWT CompositeTable widget (Eclipse.org)
• Open CSV - Java CSV parser
• Gibble - Generic cross platform (SWT) build notifier
• A couple of build radiators (screen shots)

Some legacy projects:

• pokimon - poker hand evaluation and statistical analysis, including a J2ME version
• wsunit - web services unit testing
• Tennison Tests - XSLT unit testing
• Sun SCJP Training - Copyleft training materials