any number of holsters that i thought i wanted and then didn't. most notably, i have 2 or 3 crossbreed holsters that i will probably never use. i loved the one I had for my XD and so when i switched to a glock i got another and loved it. then I started carrying a Dan Wesson Vbob and found that for whatever reason, it didn't fit quite right. in fact, none of my 1911's did. I tried 3 different crossbreed holsters. sent one back for them to adjust twice after connecting with them on the issue and ultimately gave up and switched to a comp tac MTAC. those 1911 crossbreed holsters just take up space now.
Remora holsters! to add to the holster thing... i bought a few remora's when they were on sale once. i had an office job and they honestly did OK. i bought them out of curiosity mostly. but I found that as soon as I did anything with my day outside of the office they just didnt work for me too well. and if i had any boxers on that were smooth like a lot of moisture wicking ones are, it would come out with the gun! by time i tightened my belt enough to fix the issue i would be hurting after a few hours. i now only use 1 remora and thats a pocket holster for my LCP 2. the belly band, ankle, IWB, and OWB holsters i have from them get no use at all.
at one point, i had never owned a weapon light and wanted one for my night stand gun. didnt want to spend alot not knowing if i would like it. so i bought some cheap one i found on sale with a built in laser. it was super bulky and not very bright at all. i bought a proper light and the cheapo has been in a drawer ever sense. i usually follow "buy once cry one" and every now and then when i deviate from that, i am only reminded why i follow it.
bought a plastic ammo can from HF on a whim once because it was on sale. learned i like the metal 50 cals and thats about it. so... no use.