A simple less middleware for Node's Connect, able to compile your .less files on the fly as needed. Just plug connect-less to your Connect/Express application to let it manage your .less -> .css conversions automatically.
Use NPM to install connect-less
npm install connect-less
Then load it in your app, specifying the source (and optionally destination) directory
app.use(require('connect-less')({ src: __dirname + '/public/' }));
Yes, connect-less will take care of everything.
If you want, you can read the docco-commented source code with the full description of the available options here.