URL shortening services are experiencing a renaissance in the age of Twitter. When every character counts, these services reduce long URLs to tiny forms. But which is the best to use, when so many are offered and new ones seem to appear each day? Below, issues to consider and a breakdown of popular services, including recommendations and services to avoid (the new DiggBar being one of these).

This tutorial is a practical exploration of using Python coroutines (extended generators) for solving problems in data processing, event handling, and concurrent programming. The material starts off with generators and builds to writing a complete multitasking environment that can run thousands of concurrent tasks without using threads or using code based on event-driven callbacks (i.e., the "reactor" model).