Using Variables in jQuery

I occasionally use variables and for loops with jQuery in order to change certain items on a page. A good example of this would be my obfuscation script, modified to work for any number of obfuscated e-mails on a page.

jq(".replaceAt").replaceWith("@");

obfnum = jq(".obfuscate").length;

for(i = 0; i < obfnum; i++) {
jq(".obfuscate").eq(i).attr("href", "mailto:"+jq('.obfuscate').eq(i).text());
}

Notice the use of .eq(i). I have never had a problem with this, but the same method does not work if I were to do jq(".obfuscate:eq(i)"), which is quite necessary at times I want to change something inside of .obfuscate, and not .obfuscate itself. A quick Google search helped me find the solution:

jq(".obfuscate:eq("+i+")")

Fun Backgrounds

I have seen a few sites recently that use this nifty effect: movement of certain images when you resize your browser window. It's hard to explain, so here are some examples:

http://css-tricks.com/examples/StarryNight/
http://silverbackapp.com/
https://www.redbrickhealth.com/

Pretty spiffy and super easy. They use multiple background images with attachment: scroll and various position percentages. Can't wait to try it out on a site.