While I'm scrolling down the list of invoices it would be nice if the invoice could "pop up" into view form if I hover my mouse over the invoice number. That way I wouldn't have to actually click on it, wait for the page then view the details to see what is inside the invoice, but could view those details on a simple pausing of the mouse over the invoice number. A bit like the preview of a website when hovering over a link (some browser add-ons let you do that).
"Invoice details on mouse hover"