I have been writing a Web app using Weblocks, and I have been very pleasantly surprised at the breadth and depth of the libraries available for the purpose. I would go so far as to say that the Common Lisp library problem has been solved, at least as far as writing Web apps is concerned. Here are the highlights of the packages on which my app directly or indirectly depends:

  CLSQL: database interface (I'm using PostgreSQL)
  Weblocks: widget-oriented app framework with AJAX
    Hunchentoot: web server
      CL+SSL: SSL foreign interface layer
      Babel: charset conversion
    PURI: Portable URI library
    CL-JSON
    CL-WHO: HTML generation
    CL-PPCRE: regular expressions
  CL-OAUTH: OAuth implementation
    Drakma: HTTP client
  CL-SMTP: programmatically send email
  Monkeylib-bcrypt: bcrypt foreign function interface

And almost all of these (and many more I haven't listed) are easily downloaded and installed with Quicklisp.