Zombie.js - Fast, full-stack headless testing. No actual browser needed. Runs on top of node.
Soda - Selenium Node adapter.
testling - Automated cross-browser solution
Mocha - Supports both synchronous and asynchronous testing. Node and browser frontends.
QUnit - Designed particularly for jQuery but should work with any JS code
Hiro - Runs in iframe sandbox avoiding global state leaks and conflicts.
See also Wikipedia.
Crawljax - Ajax testing and automation.
JUTE - Wraps YUI, provides code coverage. Includes both command line and web based interfaces. Provides Selenium, Capture, and V8 testing backends.
jsassert - Chaining assert.
should - BDD style assertions for node.js -- test framework agnostic