Yesterday I ordered a Nerf Maverick from eBay along with some extra arrows. These toy guns shooting soft plastic arrows are quite cool and great for performing an office war [YouTube]. I wanted to keep my arsenal civilised, as otherwise I might have gone overboard and got myself a Nerf Recon CS-6, a Nerf Vulcan automatic gun [I have a great spot between some monitors], or just this neat steampunk modded Maverick.
Also noteworthy are this awesome mod of the Nerf Firefly I found on eBay [a bit too expensive to buy though at $73.15]. There are also nice metal-painted ones and modified versions that shoot farther and faster. Big fun to annoy friends and/or coworkers with ;)