Below are collections of very useful free icon sets and vector files:
01. Open Security Architecture(OSA) Icon Library
02. Function Free Icon Set in 48×48px
03. Circular Social Media Icons
04. Chalkwork HTML – Themed Icons by Mezzoblue
05. Coquette Part 4 Icons by DryIcons
06. Credit Cards Icons in Detail by FineIcons
07. Tango Icon Library
08. Splashy Icon Set
09. Fugue Icons
10. Diagona Icons
11. WooFunction: 178 Free & Fantastic Icons
12. Chalkwork Payments
13. Siena Icon Set
14. Financial Icon Set by Visual Pharm
15. Shopping Cart and Basket (Vector)
16. 20 Free Shiny Icons by Icon Dock
17. Medical Icon Set by Smashing Magazine
18. Flag Icons by FAM FAM FAM
19. Roundy Social Networking Icons
20. Graphic River Webset Icons
21. 450+ Vector Patterns
22. Simplicio Icon Set
23. Download Charuca Present
24. Payment Icon Set (PNG) by WebIconSet.com
25. E-Commerce Vector Icons by Vectorilla.com
26. Multimedia Vector Icons by Vectorilla.com
27. Payment Icon Set (Vector) by Iconshock.com
28. Payment Method Set (512 px PNG) by Iconshock.com
29. Subtle Grunge Photoshop Brush Set by wefunction.com
30. Mobile Icon Set by WebIconSet.com (PNG)
31. eCommerce Icons by playground.ebiene.de (AI)
