Seymour (version:0.9.10) is a freeware image viewer with basic editing features, it is also portable.
Seymour is one of the newer entries in the image viewing world and it packs a good number of features in a lightweight download and shares similarities with XnView.
Images can be rated, categorized and tagged and a separate pane is available to view and find categorized images. Files can be grouped or filtered by filename, those tagged or not and those categorized or not and folders can be bookmarked too.
Beyond viewing many formats and moving and copying them there are basic editing features