Create "Table of contents" in Github wiki for H1 and H2 items.

github_toc.js

$(function () {
  var toc = $("<ul>").css("margin-bottom", "20px !important");
  $("div.main div.wikistyle h1,h2").each(function() {
    var id = $(this).text().replace(/\s+/g, "_").replace(/[^0-9a-zA-Z_.-]/g, "")
    $(this).attr("id", id)
    if (this.tagName == "H1") {
      toc.append(
        $("<li>").append($("<b>").append($("<a>").attr("href", "#" + id).text($(this).text())))
      )
    } else {
      toc.append(
        $("<ul>").append($("<li>").append($("<b>").append($("<a>").attr("href", "#" + id).text($(this).text()))))
      )
    }
  });
  $("div.wikistyle").prepend(toc).prepend($("<h2>").text("Table of Contents"));
})

As of 2 May 2012 or prior, this is no longer valid. JavaScript can't be included any longer.