Omer has released over 100 icons for web design and software. All of them are in PNG format, 32×32px. You can find those icons in PixeloPhilia Icon Set 1 and PixeloPhilia Icon Set 2. They are released under Creative Commons License and available download for free.
Set 1: http://omercetin.deviantart.com/art/PixeloPhilia-32PX-Icon-Set-157612627
Set 2: http://omercetin.deviantart.com/art/PixeloPhilia2-166570194
License: Creative Commons License