ArtForms for .NET  
   Image controls that render customizable graphics in real-time. By Progressive Consulting Technologies, Inc.
   http://artforms.progressivex.com/

Image Gallery.NET  
   Automatic image thumbnail creation, paging, template and design time support. Source code available. By Rebex.NET
   http://www.rebex.net/ImageGallery/

ImageGlue .NET  
   Generate images dynamically for the web in a variety of formats. By WebSuperGoo.
   http://www.websupergoo.com/imageglue5-1.htm

SilkWebware Image Canvas  
   Deliver real-time dynamically generated images including charts, diagrams or any other graphical application.
   http://www.silkwebware.net/products/details.aspx?id=3e4de215-9d1f-4773-8efe-5e7c2ba7dc93

TrueColorToPalette  
   Convert true color images to paletted images using Floyd-Steinberg dithering algorithm.
   http://www.asppainter.com/aspnetpalette.html

ByteSize DynaRender  
   Add dynamic image generation to WinForms and WebForms. By XHEO.
   http://www.xheo.com/products/bytesize/dynarender/

THBImage.NET  
   Displays an image and offers all ways to align and stretch the image. It supports GIF, JPEG, EXIF, PNG, TIFF, EMF, WMF, Icon. By THBComponentware. [Commercial]
   http://www.thbcomponents.com/products/prthbimgnetov.html

TIFFInfo for .NET  
   Get and Set TIF / TIFF tags as Properties. TIFFInfo works with multi page TIFF files and is 100% managed code. By BaxterSoft, LLC.
   http://www.tiffinfo.com