I've seen Common Lisp start to make a great comeback in the past few years. I started programming in it seriously about a year and half ago, and since then the packaging system (quicklisp) and libraries for it are maturing very rapidly. A lot of people are making useful libraries for practical purposes.<p>A lot of people say the language's timing was off. I couldn't agree more. However, it's starting to get a second chance. There are several open-source implementations that compile to machine code and/or support threading/networking/etc. Deployment is essentially free. For every feature that an implementation has that's not in the standard, there's a library that creates a standard, cross-implementation interface for it (for instance threading and the "bordeaux-threads" library).<p>The language is screaming fast, extremely expressive and powerful (insert mandatory macro hype here), and becoming "standardized" all over again via its libraries. I use it (Clozure CL) in production and haven't ever had an issue.