For phpBB2 there was a MOD: http://phpbbhacks.com/download/589
It let you display the most recent topics in a sidebar on the index with additional information displayed (such as last/first poster, forum name, topic_type, etc.).
You could choose how many topics to display, and from which forums it would pick them.
It also included a file which you could include on any php page on the server to show them, but that is less essential.