If you use Google Chrome 2 Beta, the developer version or a recent Chromium build, you can easily enable the user scripts support by following the instructions from this page: find or create a shortcut for Chrome's executable, right-click on the shortcut, select 'Properties' and append to the value from the Target field -enable-user-scripts (include a space before the flag). The recent builds of Google Chrome include support for user scripts and it's not very difficult to write a script that hides all the content from the new tab page. You'll still see Google Chrome's logo and some tips, but the page is almost blank. Just click on the small arrow at the top of the new tab page and disable the features you don't like.
Google Chrome 3 updated the new tab and you can now hide the thumbnails and the list of recently visited pages.
The feature couldn't be disabled from the interface and you couldn't remove the thumbnails you didn't like. Google Chrome used to display a special page that included nine thumbnails for the most frequently visited pages, a list of recent bookmarks and recently closed pages.
