I want to be able to easily add markup to various images (i.e. text and arrows and thought balloons and stuff) on my Macbook. I used to use SnagIt Editor for this on Windows. What should I use on OS X?

I'm also looking for a decent OS X blogging tool. Something exactly like Blogjet - but for the Mac. Ideally, this tool would give me brain-dead easy blogging capabilities and the added bonus of being able to automatically thumbnail or resize images I want to include in posts. I've tried Ecto, MarsEdit and Qumana and haven't seen the right combination of features yet.

(Updated: I'm going to keep plugging away using Ecto. It does seem to have the features I'm looking for, but there's added complexity to the app that doesn't need to be there - too many confusing options to choose from. It could do with a good usability scrub. Blogjet on Windows has a wayyy simpler UI and offers way better usability as a result. Funny that, Blogjet would make an excellent OS X app, and Ecto, an excellent Windows app.)