A cool feature of Mac OS X from the NeXTStep days (this feature showed up in NeXTStep 2.0) is
Services. An installed application can expose services other apps can use. In Mac OS X 10.0.x, this was only available for Cocoa apps to use. Now, Carbon apps
can use them. However,
Radio 8 is the only Carbon application I've seen make use of them.
Why is this cool?
OmniDictionary, a Mac OS X client for dictionary servers, exposes a
Define in Dictionary service. It's proven to be very handy when writing in my instant outline to check on not only the spelling but the meaning of a word. And, since it's a Service, I can use it from OmniWeb too - for checking words I'm writing as well as words I'm reading. Too bad I don't have this feature when reading
The Economist (print edition) sometimes.