I'll bite, I have a couple of long-term projects. One I've particularly enjoyed (but was not shot on RF kit, sorry) has been visiting the beautiful
Arnold Arboretum here in Boston throughout the seasons. I'll be honest though, it got started entirely by accident, and I'm ashamed to admit out of my efforts to produce something colourful for the walls of my friend's apartment. Having succeeded in that goal, (there are five 11x11 prints on display there) I then couldn't stop...
The set (which is not well-organised yet and could do with much weeding and tidying) is
on flickr, here. Here's one of my personal favourites:
Pretty much the entire set was shot with one camera and one lens, apart from two periods when I broke it that is. I somewhat wish now in retrospect I had used one film for the colour, because it would look better if it was more consistent.
I am currently on a bit of a street photography trip which would certainly be more normal RFF fare!
ps - great thread, there's some really nice and diverse stuff here!