TruHDR is a really nice HDR (High Dynamic Range photography) app that has been around a long time for iOS. It improves on Apple's built-in implementation that lets you take pictures with much better dynamic range than a single shot can provide by using an algorithm to combine three photos taken at different exposures.
Now, TruHDR is being offered at a bargain price for Mac users to try. At an introductory price of US$3.99 you can combine several exposures to produce a new image that gives you better shadow detail and avoids blown-out skies.
TruHDR claims to be able to merge up to 100 images into one HDR image, and I tried with five and seven exposure bracketed images, which worked fine. Other similar HDR apps for Mac range in price from $29.00 to $100.00 and can only merge three to seven images. Of course, most photographers won't have a hundred images to combine, but it is good to see that feature exists if it's ever needed.
The app is simple to use: click on import and select your images. They appear in a scrolling pane on the left of the app GUI. You can then do a simple merge if your shots were made from a stable tripod or a merge and align if you were shooting handheld and may have swayed a bit between exposures.