I created a patch for BlogEngine.NET which enables you to crop & resize image while being uploaded. And not only that. You can now easily insert any previously uploaded image with the new image browser.

Image Browser

New image upload with cropping & resizing

Works only with JPEG images.  Cropping is not supported in IE8.

Installation

Download & unpack it and then upload it to your BlogEngine.NET directory. You need to overwrite Add_entry.aspx and Add_entry.aspx.cs files.

Final notes

This extension works only for posts, not pages. The code is partly based on  Upload and Crop Images with jQuery, JCrop and ASP.NET article. If you have any problems, please let me know.