Optimage is an advanced image optimization tool to compress images in a visually lossless way.
Excellent compression vs quality ratio; actively developed; new/improved features with every new release
Haven't found any yet
The developer is friendly and open for requests. In fact he already had a list of new features (including some of which I was asking for) for upcoming releases that he compiled from the suggestions of other users of the application.
It took me a while to decide and shell out some money since I've been using ImageOptim (F/LOSS, donationware) for quite some time and it served me well, but on my tests Optimage was a clear winner on all fronts: final quality, compression ratio, speed, features.
Totally love the app and hope It goes well so we can have Optimage for a long time :)