Here are some good and useful icon collections that you may need for your next project.
Colorflow Icons
16 shiny Colorflow Icons created by Roberto, all Icons available in 256X256 Transparent PNG,48X48 Transparent PMG, ico and icns (for mac) format.
Colorflow Icons 2
290 shiny Colorflow Icons created by tRiBaLmArKiNgS, all Icons available in 256X256 Transparent PNG,48X48 Transparent PMG, ico format.
Aqua Blend Folder Icons
153 Aqua Blend Folder Icons created by Laurent Baumann, all Icons available in 128X128 Transparent PNG,48X48 Transparent PMG, ico format.
Money Icons
10 Money Icons created by DaPino, all Icons available in 256X256 Transparent PNG,48X48 Transparent PMG, ico format.
Business Icons
10 Business Icons created by aha soft, all Icons available in 256X256 Transparent PNG,48X48 Transparent PMG, ico format.
Business Icons
A collection of 12 packs with weather icons
Comrade Matryoshka
Cool icons in all sizes, Windows, Mac and PNG formats
Credit Card Icons
Credit Cards is a collection of icons for websites which accept online payments like online shops or services. Credit Card icons are in GIF format. There are currently about 20 different icons.
15 Free Origami Icons
Origami Free Set is a set of 15 icons, originally designed by Jack Cai from Double-J Design, and brought to you by IconDock. All icons are completely free for both personal and commercial use.
Flavours Icon set
Flavours Icon set was designed by Oliver Twardowski, a graphic designer from Bonn, Germany, the set aimed to help designers in their Web and user interface designs, containing 177 icons in a resolution of 48×48 pixels.
A really nice collection of icons here. The business and money sets will come in handy.