Whenever I find a nice resource, I try to add it to this list.

C#:

• Implementing the Singleton Patttern in C# (discussion about different implementations)
  http://www.yoda.arachsys.com/csharp/singleton.html
• Introduction into the Model-View-Control pattern with C#
  http://www.c-sharpcorner.com/UploadFile/rmcochran/MVC_intro12122005162329PM/MVC_intro.aspx
• Good series about UI Code in C#
• http://codebetter.com/blogs/jeremy.miller/archive/2007/07/25/the-build-your-own-cab-series-table-of-contents.aspx

Perl:

• Perl Nachrichten
  http://www.perl-nachrichten.de/
• Foo Magazine, German Perl magazine
  http://foo-magazin.de/