jquery.background-noise.js

jQuery.fn.noisy = function(opacity) {
  if (typeof(opacity) === 'undefined') {
    opacity = 0.1;
  }

  var wrapper = jQuery(this).wrapInner('<div />').children();
  var canvas = document.createElement("canvas");
  canvas.width = 100;
  canvas.height = 100;
  var ctx = canvas.getContext("2d");
  var x, y;
  for (x=0; x<canvas.width; x += 1) {
    for (y=0; y<canvas.height; y += 1) {
      var r = Math.floor(Math.random() * 75);
      var g = Math.floor(Math.random() * 75);
      var b = Math.floor(Math.random() * 75);
      ctx.fillStyle = "rgba("+r+","+g+","+b+","+opacity+")";
      ctx.fillRect(x, y, 1, 1);
    }
  }

  wrapper.css({
    'background-image': "url("+canvas.toDataURL("image/png")+")",
    width: '100%',
    height: '100%'
  });
};

jquery.color-tile.js

jQuery.fn.colorTile = function(opacity) {
  if (typeof(opacity) === 'undefined') {
    opacity = 0.1;
  }

  var wrapper = jQuery(this).wrapInner('<div />').children();
  var canvas = document.createElement("canvas");
  canvas.width = 100;
  canvas.height = 100;
  var ctx = canvas.getContext("2d");
  var x, y;
  for (x=0; x<canvas.width; x += 10) {
    for (y=0; y<canvas.height; y += 10) {
      var r = Math.floor(Math.random() * 255);
      var g = Math.floor(Math.random() * 255);
      var b = Math.floor(Math.random() * 255);
      ctx.fillStyle = "rgba("+r+","+g+","+b+","+opacity+")";
      ctx.fillRect(x, y, 4, 7);
    }
  }

  wrapper.css({
    'background-image': "url("+canvas.toDataURL("image/png")+")",
    width: '100%',
    height: '100%'
  });
};

jquery.grain.js

jQuery.fn.grain = function(opacity) {
  if (typeof(opacity) === 'undefined') {
    opacity = 0.1;
  }

  var wrapper = jQuery(this).wrapInner('<div />').children();
  var canvas = document.createElement("canvas");
  canvas.width = 100;
  canvas.height = 100;
  var ctx = canvas.getContext("2d");
  var x, y;
  for (x=0; x<canvas.width; x += 5) {
    for (y=0; y<canvas.height; y += 5) {
      var r = Math.floor(Math.random() * 255);
      var g = Math.floor(Math.random() * 255);
      var b = Math.floor(Math.random() * 255);
      ctx.fillStyle = "rgba("+r+","+g+","+b+","+opacity+")";
      ctx.fillRect(x, y, 1, 1);
    }
  }

  wrapper.css({
    'background-image': "url("+canvas.toDataURL("image/png")+")",
    width: '100%',
    height: '100%'
  });
};

jquery.graph-paper.js

jQuery.fn.graphPaper = function(opacity) {
  if (typeof(opacity) === 'undefined') {
    opacity = 0.1;
  }

  var wrapper = jQuery(this).wrapInner('<div />').children();
  var canvas = document.createElement("canvas");
  canvas.width = 100;
  canvas.height = 100;
  var ctx = canvas.getContext("2d");
  var x, y;
  for (x=0; x<canvas.width; x += 10) {
    for (y=0; y<canvas.height; y += 10) {
      var r = Math.floor(Math.random() * 255);
      var g = Math.floor(Math.random() * 255);
      var b = Math.floor(Math.random() * 255);
      ctx.fillStyle = "rgba("+r+","+g+","+b+","+opacity+")";
      ctx.fillRect(x, y, 1, 1);
    }
  }

  wrapper.css({
    'background-image': "url("+canvas.toDataURL("image/png")+")",
    width: '100%',
    height: '100%'
  });
};

jquery.notebook.js

jQuery.fn.notebook = function(opacity) {
  if (typeof(opacity) === 'undefined') {
    opacity = 0.1;
  }

  var wrapper = jQuery(this).wrapInner('<div />').children();
  var canvas = document.createElement("canvas");
  canvas.width = 100;
  canvas.height = 100;
  var ctx = canvas.getContext("2d");
  var x, y;
  for (x=0; x<canvas.width; x += 1) {
    for (y=0; y<canvas.height; y += 15) {
      var r = Math.floor(Math.random() * 5);
      var g = Math.floor(Math.random() * 255);
      var b = Math.floor(Math.random() * 255);
      ctx.fillStyle = "rgba("+r+","+g+","+b+","+opacity+")";
      ctx.fillRect(x, y, 1, 1);
    }
  }

  wrapper.css({
    'background-image': "url("+canvas.toDataURL("image/png")+")",
    width: '100%',
    height: '100%'
  });
};

Packaged into a single jQuery plugin: http://jsfiddle.net/methodin/gPejK/

whoa jsfiddle rocks!

Haha indeed. BTW packaged it up @ https://github.com/methodin/jQuery-Canvas-Background

awesome. I love github