Isn't npm default ./node_modules?
$ npm install socket.io
socket.io@0.9.14 node_modules/socket.io
├── base64id@0.1.0
├── policyfile@0.0.4
├── redis@0.7.3
└── socket.io-client@0.9.11 (xmlhttprequest@1.4.2, uglify-js@1.2.5, active-x-obfuscator@0.0.1, ws@0.4.25)
$ ls
node_modules