I constantly receive questions about IE8 resources and thought that it is useful to aggregate them in a blog post:

IE8 Team Blog: http://blogs.msdn.com/ie/

Personalize IE8 through web services: http://blogs.msdn.com/ie/archive/2009/02/03/personalize-ie8-through-services.aspx

Visual Search Providers

i. Extend IE8 through Visual Search Providers  http://msdn.microsoft.com/en-us/library/cc891507(VS.85).aspx

ii. Search Suggestions Format: http://msdn.microsoft.com/en-us/library/cc891508(VS.85).aspx

Accelerators

i. IE 8 Search Accelerator Developer Guide: http://msdn.microsoft.com/en-us/library/cc289775(VS.85).aspx

ii. Open Service format specification for IE8 Accelerators: http://msdn.microsoft.com/en-us/library/cc304163(VS.85).aspx

Web Slices

i. Web Slice format specification: http://msdn.microsoft.com/en-us/library/cc304073(VS.85).aspx

ii. All about Web Slices: http://msdn.microsoft.com/en-us/library/cc956158(VS.85).aspx

iii. IE8 Web Slice guide: http://msdn.microsoft.com/en-us/library/cc848871(VS.85).aspx 

iv. Authenticated web slices: http://msdn.microsoft.com/en-us/library/dd565670(VS.85).aspx

v. How do I build a web slice (video): http://msdn.microsoft.com/en-us/ie/cc304683.aspx

vi. Step by step guide to create a web slice: http://blogs.msdn.com/giorgio/archive/2009/05/01/h1n1-flu-swine-flu-web-slice-step-by-step.aspx

IE8 Case studies

i. Popular IE8 services: http://www.ieaddons.com/en/popular/

ii. eBay IE8 services: http://ie8.ebay.com

iii. Amazon IE8 services: http://www.ieaddons.com/en/search/?search=amazon

iv. Wal-Mart IE8 services: http://www.ieaddons.com/en/search/?search=walmart

Hope this helps.

-Hanu