I love a lot of things about Messages for Mac. Even though it has numerous issues, the ability to receive and respond to iMessages, as well as AIM, Jabber, etc. if you really must, makes it enormously useful. Except, searching on it absolutely sucks. The moment you start typing in the search box, Messages freezes in a way that makes iTunes seem snappy. It's not good. It's the opposite of good. Enter Chatology.
Flexibits, best known for Fantastical, are past masters at fixing the pains that ail us. As they did for calendaring, they're now doing for message search.
Here's the deal: Enter a search term and Chatology shows you a beautifully, practically arranged set of results. It's dynamic, so if you have an existing search up, and a new message comes in that meets the same criteria, it just shows up there. You can also isolate images or links, so you find only exactly what you want.
I've been using the beta for a few weeks, and it's been invaluable in locating URLs, passwords, and other information that Messages by itself made arduous to track down. Despite being on the beta, I bought a copy the moment it launched, and it's running cheerfully beside this very window right now.
All that said, it's a tool meant for power Messages users, for those who depend on being able to find information they need immediately when they need it. And it's priced for just that type of person.
If your personality or your career demands it, Chatology can get you just that information, quickly, elegantly, and powerfully. If you're not sure whether, for you, it'd be a nice to have rather than a must have, there's a free trial so you can find out.