This page contains a log of interesting (IMO) questions and answers, in no particular order, from the official Reactive Extensions (Rx) forum. I'll add to this list as I come across discussions that I feel are noteworthy. Perhaps it will be more of a personal log so that I don't have to search for my own answers to repetitive questions, though I'll certainly include others' answers as well.

Update: As of late 2014, I've been much more active on Stack Overflow than the Rx forums. That's just where the action is now. See my answers here.

Note that the titles of the posts unfortunately don't always indicate the focus or importance of the discussion.

• Scenario that uses "SubscribeOn" - October 22, 2011
  
• It's hard to reason about Publish - July 14, 2011
  
• Homework: Find the Call/CC operator - November 18, 2009
  
• Reactive Parser Combinators - May 01, 2010
  
• What if an exception is thrown by the observer in OnNext? - January 21, 2010
  
• About the contracts in RX (exceptions and blocking) - January 22, 2010
  
• Best practise on orchestrating sequences in series - August 14, 2012
  
• Making sequential async calls easy... - March 24, 2010
  
• Rx: Piecing together multiple IObservable web requests - April 05, 2010
  
• Speed optimization - reusing the same object (reference type) for IObserver.OnNext()! - August 14, 2012
  
• ObserveOn doesn't observe on requested thread? - July 07, 2011
  
• About Rx Schedulers and Parallelism - August 02, 2012
  
• sliding window - September 16, 2011
  
• Rx and Ix Query Comprehension Syntax Keywords in C# - September 21, 2012
  
• Checklist for Creating Rx Operators - September 19, 2012
  
• How to do a negative join? - February 13, 2011
  
• Filling gaps in increasing sequence - February 10, 2011
  
• Reactive Conversions Between OnNext, OnError and OnCompleted - April 30, 2010
  
• Exception handling and EventArgs.Error (WCF) - December 11, 2012
  
• How to use Let and what is the LINQ "let" equivalent in Rx? - March 30, 2010
  
• Scan with async seed - February 21, 2013
  
• Performance penalty with 1000s of calls to Observable.Interval? - May 09, 2013
  
• Why does managed thread id keep changing? - August 14, 2014
  
• Create TouchClick from TouchDown and TouchUp - September 28, 2014
  
• How to use Rx when "T" is a large, expensive object - October 8, 2014
  
• How to window/buffer IObservable<T> into chunks based on a Func<T> - October 15, 2014
  
• Reactive Extensions combining two IObservables into one - October 29, 2014
  
• Another discussion on Glitches and Rx - January 16, 2015