I dealt with it by specializing on the C#-Windows platform. Allows me to hold 5x the language trivia I would able to hold if I worked on 5 different languages and platforms :P.

It's easier in the .NET world because a lot of shops for better or worse go pure Microsoft so there is a standard set of technologies and accompanying trivia you can learn. Unfortunately you won't get to work with best of breed products, but the upside is you'll get to familiarize yourself with enough technologies that you can get up and running fairly quickly.

   Language : C#
   Database : Sql Server
   ORM : Entity Framework
   IDE : Visual Studio + Resharper
   Client Side UI : WPF
   Web Server : IIS
   Web : Asp.net MVC/Classic etc...
   Client OS : Windows
   Server OS : Windows
   Development OS : Windows
   Cloud : Azure
   Logging : NLog or Log4Net
   Code Generation : T4   
   Source Control : TFS 
   Build Server : TFS
   Unit Testing : MSTest
   Build language : MSBuild
   Deployment : Wix or ClickOnce
   Mocking Framework : Moq or Fakes
   etc...
   

(This list is ignoring many of the different technologies that have been discarded by Microsoft such as winforms, COM, VB6, etc..)