RSpec: I’m on the RSpec core team.
Ripple: I’m on the Ripple core team.
VCR: Ruby gem to record your test suite’s HTTP interactions and replay them during future test runs for fast, deterministic, accurate tests. Featured on:
Fractal Composer: Java library to algorithmically generate fractal compositions using self-similarity based on an initial seed.
Test Benchmarker: A tool for benchmarking ruby Test::Unit tests.
See my github profile for a complete list.