Ezthumb - A video thumbnail generator based on ffmpeg.
Img.vision - Image hosting & video hosting for eCommerce sellers
Video Thumbnails Maker - Allows you to make thumbnails (caps, previews, screen-lists) and screenshots of video files.
UploadHouse - Thumbnail and resize your photos and images
MoviePrint - MoviePrint lets you create screenshots of entire movies in an instant.
ImageVenue - ImageVenue is a great online hosting service that allows uploading pictures for showing creative works with a simple-to-use technique.