I'm collecting the "kanzenban" ("complete edition") of the manga that came out last year in Japan. These are big volumes with great paper quality and color splash pages, as well as new cover art by Takeuchi Naoko which you can see
here. The "kanzenban" edition is 10 volumes (and also 2 volumes of Codename: Sailor V), I have vols. 1-4. 1-2 is the Dark Kingdom arc and 3-4 is Black Moon.
Next to it is the Viz Blu-ray boxset of season 1. I preordered both parts from rightstuf.com so I got the bonus items like the medallion and the set of character pictures. My S.H. Figuarts figure of Sailor Moon is also displayed.
I just got the Figuarts for Sailor Jupiter and Venus today, they're not displayed yet...my birthday was on the 1st and I got a ton of amazon gift cards so I thought I'd put them to use and order the Figuarts for the rest of the inner senshi.

Mercury and Mars are coming soon~
My complete set of the Kodansha USA translated manga along with a vintage Sailor Moon piggy bank.
Plushies of Sailor Moon and Chibi-Moon.
On the left: A deluxe volume of the "Kaguya-hime no Koibito/Princess Kaguya's Lover" side-story from the manga, which the S movie was based on. This volume was published around the time the S movie came out in Japan.
On the right: An official guide to Sailor Moon R.
And finally I have some old figurines of Sailor Moon and Sailor Venus that came with trading cards, but they're pretty worn-out and not in great condition.
I also used to have a couple volumes of the old TokyoPop translation of the manga (as well as a couple chapters printed in American comic format), as well as the dubbed R, S and SuperS movies and subbed R movie on VHS...and the Lunarock CD.