Rails: use friendly (non-numeric) URLs.

article.rb

##
# Use the +handle+ instead of the +id+ for URLs.
#
def to_param
  handle
end

articles_controller.rb

# GET /articles/1
def show
  @article = Article.find_by_handle!(params[:id])
  ...
end

# GET /articles/1/edit
def edit
  @article = Article.find_by_handle!(params[:id])
end

...