Opera lets you bypass the anachronistic 'tab' metaphor completely:
Use Ctrl-Tab to switch between tabs the same way you Alt-Tab between windows. Close a tab with Ctrl-F4, similar to closing windows with Alt-F4.
Firefox with Vimperator does even better - t to open a tab to a url or search string, d to close a tab, Ctrl-n and Ctrl-p to tab between them.
Of course, Chrome's Vim extension replicates similar functionality. Either way, reducing mouse-keyboard context-switching is useful.