By default, your chat list will be sorted by the people with whom you communicate most often. However, you also have the option of changing to alphabetical sort order.
- Click Options from the bottom of your chat list.
- Under Show in chat list: click All contacts or Top 250.
In iGoogle and orkut:
- Click Actions from the bottom of your chat list.
- Under Sort chat list: click Alphabetical.
You can change this back to popularity by selecting Most Popular instead.
If you would like more contacts to show, you can always resize your chat list.