Like everyone else I use NetNewsWire, Transmit, Adium etc, but there are also a stacks of less well known indie apps out there that do what they do brilliantly, and don’t get enough recognition for their greatness.
Here are 5 of them:

My favourite 3rd party application of all time. Hands down. I’m using it right now to write this. No other journaling, text-snippet managing, or GTD app has come close to tearing me away from my beloved MacJournal. Checkboxes integrated into text editing is simply an awesome idea.

Couldn’t live without it. If you are learning a foreign language (in my case Russian) TranslateIt is just invaluable. It’s just like Apple’s dictionary except for the language of your choice, and it also includes a cool scanning mode just like Apple’s mini-dictionary window for looking up words quickly on the web.

Apple’s Fontbook should be like this app. When I saw it, I gasped. Brilliantly designed and super useful for finding the right font for your project.

I love physics and for anyone studying it or using physics related formula in school or day-to-day life, you can’t go past Physics 101.

Terrific app for making slideshows. Some of the effects this guy has created in Quartz Composer are just stunning.