Simulate HDR is a plugin for The GIMP that creates two layers from a single image simulating an underexposed and a overexposed shots, creating a High Dynamic Range image.
It can create a tone mapping layer to compress the color range of the image.
L.E.I.C.A. (Long Exposure Internet CAmera) is an application that takes input from your webcam, or v4l2 device, and makes a long-exposure image.
Until now there's only a python binding for this app, soon there will be a C/C++ SDL one