Binary dependencies of sites using this library

DotNetOpenAuth.dll the only runtime dependency for web sites to use this library.
DotNetOpenAuth.pdb may be useful for debugging purposes.
DotNetOpenAuth.xml provides Intellisense during development.
DotNetOpenAuth.Contracts.dll Compile-time code contracts for use by applications that reference DotNetOpenAuth.dll to help web developers avoid mistakes and unhandled exceptions.
log4net.dll If present, will allow for recording log messages this library emits.
Microsoft.Contracts.dll enables contract compile-time and runtime enforcement, but currently only used for developing DotNetOpenAuth itself.