What do you want to be able to customize?
gills: Some simple tagging and a way to add links to custom views on the top bar -- so I can have a view of all the "Review my Startup" submissions and the "YC Startup XXX launched today" submissions.  (def customize-nav-bar
    (lambda ()
      (filtered-view 'Startups'
                     (lambda (submission)
                       (tagged-as 'startup'))
      (filtered-view 'YC Startups'
                     (lambda (submission)
                       (tagged-as 'YC startup'))
      (filtered-view 'Ask HN'
                     (lambda (submission)
                       (tagged-as 'Ask'))