Chilkat provides me with a vast library for use with my C# projects. The ones in particular that i use is for reading CSV files and ZIP compression library. It does what it says.

Chilkat is a great library that is meticulously designed and tested. It not only comes with great documentation but also a lot of code samples and above all, great support! Their support replied to all of our questions promptly and provided us guidance for fixing the issues in just a few hours. It is worth every penny!

Easy to use, it do all the dirty job you don't want to do by yourself.