Note there is a larger collection of examples in the knitr-examples repository on GitHub. This page is more for the documentation purpose. You can take a look at the collection of knitr applications by other users as well.
2011-12-03 Minimal examples · Examples for Rnw, Markdown, HTML and LaTeX
2011-12-04 Cache · Examples for the cache feature
2011-12-05 Manual · The package manual
2011-12-06 LyX · Using knitr with LyX
2011-12-07 Code Externalization · Use an external R script with your document
2011-12-08 Beamer · Using knitr in beamer slides
2011-12-09 Graphics · Power of graphics in knitr
2011-12-10 Listings · Using knitr with listings
2012-01-14 Chunk Reference/Macro · How to reuse chunks
2012-01-18 Child documents · Input child files into the main document
2012-01-22 Package vignettes · How to build package vignettes with knitr
2012-01-25 Control output · Manipulate six types of chunk output and inline output
2012-01-26 Quick reporting · Build a report based on an R script
2012-02-01 Org-mode · Use knitr in Org-mode
2012-02-02 RStudio · knitr support in RStudio
2012-02-11 Pretty printing · Print highlighted source code of a function
2012-02-12 Upload images · Publish images from chunks in the web
2012-02-24 Sweave · Transition from Sweave to knitr
2012-02-27 Eclipse · Configure Eclipse to work with knitr
2012-02-29 Package framed · Default LaTeX style in knitr
2012-03-16 Editors for knitr · Work with Emacs, Texmaker, TeXShop, WinEdt and TextMate, etc
2012-05-01 HTML5 slides · making HTML5 slides with pandoc and knitr
2012-05-04 Language engines · Use other languages in knitr
2012-11-09 JavaScript · Combine R and JS applications like D3
2013-02-10 WordPress · Publish blog posts from R + knitr to WordPress
2013-03-06 Pandoc · Convert Markdown to other formats via Pandoc
2013-03-11 knitr showcase · Examples from other users