SharpCompress is a fully managed C# library to deal with many compression types and formats.
MIT License
Read the file listing of a .zip archive without downloading the whole thing.
#ziplib is a Zip, GZip, Tar and BZip2 library written entirely in C# for the .NET platform.
Tiny unzip helper class for .NET 3.5 Client Profile and Mono 2.10, written in pure C#.