Machinery HDR Effects is a powerful photo editor which uses HDR technology to enhance the colours, contrast and details of a digital image.
If you're new to HDR (High dynamic range imaging) then that doesn't have to be a problem. At a minimum, you can open a single JPG, browse various filter thumbnails to see the effects available, and double-click whatever you like to apply it.
There are various panels and adjustments for brightness, contrast, black and white levels, colours, saturation, sharpness, and more. Again, this doesn't have to be difficult - it starts by simply dragging a slider - but there are many more advanced tools if you know what you're doing.
If you've plenty of HDR experience then you can jump right in, use one of the program's three intelligent merging methods to combine your chosen frames, which variously work to eliminate halo effects and optimise contrast (you can have them auto-aligned with any ghosting removed, too).
To get a quick feel for exactly what the program can do, check out the amazing images on the Samples page, or see other people's work on the Machinery HDR flickr pool and Facebook page.
Or, if you want to drill down into the fine detail, the online manual covers it all.
Please note, although the trial version has various restrictions - can't use it for high resolution photos, doesn't save 16-bit TIFF, can't use it for commercial work - there's no watermark or anything too heavy-handed. If you're a home user who just wants to optimise a few pictures then you may be able to produce good results without having to buy anything.
An excellent photo editor, particularly if you're familiar with HDR (although novices can get a lot from the program, too).