Fastworks.js (License: GPL3, npm: fastworks) by Robee Shepherd is an alternative to Connect. It includes "stacks" for organising middleware, and middleware for routing, static files, compression, cookies, query strings, bodies in various formats (including JSON), and a lot more. It can also work with Connect modules.
That Lactate module sounds promising. On the subject of performance, one motivation for developing Fastworks.js was speed, but as of yet it doesn't include benchmarks or tests. Hopefully the author will include these at a later date so we can see how it shapes up against Connect.
Probability.js (License: MIT) by Florian Schäfer is a fascinating little project that helps call functions based on probabilities. Functions are paired alongside a probability so they'll only be called some of the time.
That doesn't sound useful on the surface, but the author suggests it could be useful in game development. Although if you've played the recent XCOM game you may be disillusioned by randomness in games, which is actually quite a well-trodden topic in the games development community. Analysis: Games, Randomness And The Problem With Being Human by Mitu Khandaker is an interesting analysis of games and chance.
Colony (GitHub: hughsk / colony, License: MIT, npm: colony) by Hugh Kennedy displays network graphs of links between Node code and its dependencies, using D3.js.
The network can be navigated around by clicking on files -- the relevant source will be displayed in a panel. Files are coloured in groups based on dependencies, so it's an intuitive way to navigate complex projects.