I think the default icons for file associations in 7zip are REALLY ugly. I came across an app called XPize that replaces several icons from windows system files and in apps such as 7zip. The issue was that the replacement 7zip icons were only for 4 of the compression formats (zip, 7z, iso and tar). Using those icons as a guide, I created a full replacement icon set. They can replace all 15 icons embedded in 7z.dll. Use ResourceHacker to make the changes.