The uwawidget.php library allows a facilated use of UWA-Widgets with PHP. It gives you access to the preferences and some convenience-functions. You can test a limited amount of Widgets here, but in theory, it should work with every UWA-compliant Widget.
You can find widgets on the Netvibes Widget Directory. Look at the Source link in the widgets details. Take care, just UWA-Widgets work (orange icon), Mini-APIs sometimes do.
Unfortunately, the BlogMethod is buggy sometimes, please see the Board.