Designing icons is hard. Designing quality icons is harder. That's why it's great when a free resource pops up that provides over 100 free icons for your use in iPhone application designs. These icons are perfect for tab bars or toolbar use.
Often times we don't use these icons verbetam but they provide a valuable design language and starting point that offers some level of predictability and consistency across apps.
Get them over at http://www.glyphish.com/