This project is currently hosted here: 

https://github.com/FObermaier/DotSpatial.Plugins (version for DotSpatial 1.7)

https://github.com/Adriaanse/DotSpatial.Plugins (upgraded to DotSpatial 1.8)

Note that no NuGet packages have been released yet For DotSpatial 1.8 so you need to reference them from Lib manually