For enhancement:
First you need to make this site browser compatible. I was browsing the site using Mozilla Firefox (my default browser) and was not able to access (not clickable) the menu. For an example, all of our sites that developed officially must be compatible with IE (6, 7, 8), Firefox (2, 3) and Safari browsers.
From admin site, you should be able to get/view the information of users (not only affiliates): List of users, when they will expire, Newly registered users to accept/deny their account etc. You should be able to pay for any user from admin site using Paypal/directly. Suppose someone paid to you physically and you want to adjust the amount for this user.
In "Top Sales Report" if you want to select any date, it is requesting/posting the page to server site and it's time consuming to select/ change any date. This should be done in client end.
"Groups information" information is showing only for a single affiliate and child affiliates and users are showing commonly and there is no distinguished column/identification.