EggCafe 7Zip cookie example This is an example (zipping cookie) with the DLL of 7Zip.
CodePlex Wrapper This is an open source project that warp zipping function of 7z.
7Zip SDK The official SDK for 7zip (C, C++, C#, Java) <---My suggestion
.Net zip library by SharpDevelop.net
CodeProject example with 7zip
SharpZipLib Many zipping