ThM, of BoardMod and YaBB, has updated a handy new mod for YaBB 2.2.1 to 2.2.3 and announced it on BoardMod... Newest Topic Overview 1.2.  Here is an excerpt from ThM's announcement:

Description:
 
This Mod add a Drop-Down Selection Field into the Info-Center. You can select 5, 10, 25 or 50 newest Topics for Viewing in a Overview. It's possible to enable/disable these Option in your Admin Panel - Global Settings - Tab Posting.