The new version of Internet Explorer finally adds a new tab page that shows your most recently used sites, but sadly, you can't customise the display from the options panel. What you can use, however, is a registry hack.
To make the change for yourself, you can simply head over to the HKEY_CURRENT_USERSoftwareMicrosoftInternet ExplorerTabbedBrowsingNewTabPage key in the registry editor, and then change the value of NumRows to the number of rows you'd like to see on the new tab page. You'll have to restart Internet Explorer before the change kicks in.
If you'd rather not mess around with the registry editor, you can simply hit the link for a set of downloadable registry hacks for each number of rows. You'll need to restart Internet Explorer after making the change.
Showing more sites on about:tabs [EricLaw's IEInternals]