I also really like this script. Very handy in many situations.
Sometimes it appears in not mail fields. In this cases it's little annoying of having the suggestion list in front of the next input field. So I added margin-left: 25px; to the div.autosuggest class. Now I can keep on filling out my forms. Actually it would be better to let the box disappear when leaving the input field.

Thanks for implementing some of my suggestions. It would be nice to somehow store the address book locally and refresh it every x hours/days, but the current implementation is pretty good.

I messed around with this script on my computer, and made it so that (at least on firefox 2, linux) it will allow users to enter comma separated lists of emails. hope this helps!

In _b.AutoSuggest.prototype.doAjaxRequest, change the beginning of the function to look like this:

      _b.AutoSuggest.prototype.doAjaxRequest = function (input)
      {
      	// check that saved input is still the value of the field
      	if (input != this.fld.value)
      		return false;
      
              // only look at the text after the last comma
              var comma = -1;
              while ( input.indexOf(",", comma) >= 0 ) {
                      comma = input.indexOf(",", comma) + 1;
              }
              if ( comma >= 0 ) input = input.substring(comma);
              // trim
              input = input.replace(/^\s*([\S\s]*?)\s*$/, '$1');
      

and in the function _b.AutoSuggest.prototype.setHighlightedValue, change the first part of the function to look like this:

      _b.AutoSuggest.prototype.setHighlightedValue = function ()
      {
      	if (this.iHigh)
      	{
                      // get the text up until the last comma
                      var input = this.fld.value
                      var comma = -1;
                      while ( input.indexOf(",", comma) >= 0 ) {
                              comma = input.indexOf(",", comma) + 1;
                      }
                      if ( comma >= 0 ) input = input.substring(0,comma) + " ";
                      else input = "";
      
      		this.sInp = this.fld.value = input + this.aSug[ this.iHigh-1 ].value;
      

This would be a great addition to the Better Gmail 2 extension for Firefox (lifehacker.com)

For Google Apps, the URL is: https://mail.google.com/a/EXAMPLE.COM/contacts/... .

Other suggestions would be to add support for multiple addresses separated by commas and to no longer change the title of the script (it's installed as a new script).

Some suggestions:
1) improve the excluding pattern: http*://*.google.com/*, http*://google.com/*
2) increase the delay for hiding the suggestions. They disappear way too quickly. A better idea is to hide the list only when you click somewhere in the page.
3) Only match prefixes: if I type "ne", don't match janet because it doesn't start with "ne". Learn from Gmail's autocomplete feature.
4) Don't use the CSV file. Try this XML file: http://docs.google.com/c/data/contacts?max=1000
5) Stop highlighting names when you are only matching email addresses.
6) Start to match names. They are more important than email addresses.

So is this pulling contacts from my Gmail list or my Google Apps Gmail list? If regular Gmail, how can I force it to use Apps, whilst remaining logged in to both?

Hiii, I liked this script.. Can u tell me the license? Can i modify the script and host it?

[Addendum/Update: Okay, I see it working for me when I try Hotmail (ugh). No problems so far, and it's definitely different than the dropdown I was getting with Reader (though I still insist Reader didn't work for me that way before today :-), so that must be something else unrelated. In any case, so far, so good since my memory is mush when it comes to addresses.]

@Chuck this script is disabled on google.com; I think Reader typically pulls from your address book anyway

Just installed to try, hopefully it works.

Works for me, I'm happy to report ... I'm thinking maybe it was pulled, edited, and re-upped?, as my first two attempts to install brought me to the homepage, not the install script dialog ... on the third attempt, I got the usual install routine and a quick test (sending an e-mail to a Gmail contact from within Google Reader) was successful.

Love the idea of this script, but can't get it to work. My error console says:

Error:
Source File: file:///[....]./gm_scripts/google_contacts_autocomp/google_contacts_autocomp.user.js
Line: 1823

This is the line:
window.addEventListener('load', go(), false);