Remove “Avatars” from titles of BuddyPress core widgets

In the BuddyPress core widgets, remove “Avatars” from the widgets’ title.

Change: Who’s Online Avatars
to: Who’s Online

Change: Recently Active Member Avatars
to: Recently Active Members

You can edit bp-core-widgets.php (search for “parent::WP_Widget”) or, alternatively, see “Customizing Labels, Messages, and URLs“.

http://wordpress.org/extend/plugins/buddypress/