This is a pretty narrow post, but a few people might find this useful since I’ve been frustrated by the preview function in MarsEdit, a fairly popular Mac blog editor, with WordPress. WordPress by default assumes you want new paragraphs if you bother to hit return twice.
Unfortunately, with prior versions of MarsEdit it just smashed everything all together in the preview window which made proofing the layout on a longer post pretty annoying. Now you can just switch the Formatting pulldown at the bottom of the preview window to Convert Line Breaks and everything has line breaks again in Preview. You can pull down the beta here.
It’s not a super fancy feature rich blog editor, but that’s exactly what I’ve come to like about it. You just pop it up, type in your post, and send it off. The interface is very similar to composing in pretty much any email client, so it’s very familiar.