How can we improve WHMCS?

We often visit /billableitems.php?status=Uninvoiced and use a calculator to manually add up all the line-items to get the total of uninvoiced items. We typically add this total to the Income Forecast report, to get a true projection of what we'll be invoicing next month..

Long story short, it would be great to have a sub-total at the bottom of /billableitems.php?status=Uninvoiced

Thank you