For my online and offline RSS needs I've been using Shrook for a while - but since recently I got an iPhone the issue of syncing it with my mac gracefully has become quite important.

Shrook does have a complementary iPhone reader, but unfortunately it lacks two important features:

1) it doesn't remember the history of your 'mobile' rss readings

2) more importantly, it doesn't let you 'tick' a news item for later reading (so that I can check it out better on the computer, with a normal size screen)

Well the guys at NewsGator have done it all!!! You can download the free RSS reader they provide that has all the features I was talking about (and of course it also syncs with a free online version of the software) Neat!