Just a few random ideas for active gear, note the turret is the 6th iteration of the idea and isn't 100% serious.
note I use PvE for description of loot runs (no clue why)
looks: google it.(think a high end one that can blind people that look at it)
use: flares are used as a diversion item, example in PVP players with in the range of a flares light have 20% less chance of being hit (do to the flares light) if used in PVE, zombies in a range will move to the flare before attacking the survivors (good for solo runs)
looks: google it
use: stun grenades can incompasitate survivors and zombies alike (can cause zombies to attack each other). its main use is in PVP where it can instantly suppress people that are in its blast range, while in PVE it will cause zombies that are cought in the blast to "retreat" from combat.
info: the riot gear is only active gear in the sense of damage, do to heavy use all riot gear in union city is damage to the point that they can be used 3 maybe 4 times before breaking, riot gear is the rarest armor in the game and the most protective(replacing the who player model and equipping cosmetic gear when used). though it can only be used a few times riot gear makes its owner a god in armor.
use: +100 HP and 70% protection from all damage types
note: unlike other gear types there is only a purple variant of this one, that being the UCPD riot gear. it is also the only gear with a limiter to one user per raid or loot (for balance)
uses before breaking: 3 loots or raids.
looks: alliance banner
use: this rare item is only given to alliances for some reason or another, this one use item allows you to "claim" a loot area on your map, this will allow you to loot it once very 8 hours for 7 days instead of once every 24 hours. (not that useful but would still be fun
TURRET (more of a joke then a serious suggestion)
looks: similar to this http://images2.wikia...entry_Decay.jpg
info: mainly used for auto loots, and rarely encountered at military bases, auto turrets are a mid damage (10-30) motion sensor gun with a range of about 15. the auto turrets are only found in high ranking military outposts and areas do to there rarity and use as area denial.
use: auto turrets are used as a 6th gun on missions, holding 200 rounds (added to mission ammo cost), they can hold an area from infected or be manually aimed to suppress a sniper. the main down side to the turret is its health, each turret only has 50 HP and can not be healed, though they can be picked back up during battle(can't be replaced) in order to keep the item.
note: if manual aimed its auto target system will be disabled meaning it will only fire at the aimed target and nothing else (even after targets dead)