You can't start playing EVE without hearing about all of the balance issues. "Nerf the Drake", "Give a 4th bonus to Assault Frigs", "Blasters Suck", etc. You get the impressions that EVE is full of balance issues so only a handful of popular items are ever seen. I have a different take on it. While some items do suck, I can never understand why so many OMFGPWN items are almost never seen. Here is my list of the top 5 seriously overpowered items in EVE, that you almost never see fitted.
5. Target Painters: One of these fitted on one ship in fleet increases the turret tracking for all ships in the fleet more than a scripted tracking computer, plus increases damage for all missiles, plus increases lock time for all ships.
4. Smart-Bombs: Always hits for full damage. Immune to ECM. Does not need to wait for a lock to fire. Hits every single target in range simultaneously. Hits missiles, bombs, drones.
3. Bombs from multiple bombers: One bomber by itself is pretty common, but also pretty useless. The fact is that 7 bombers firing at the same time can destroy most non-cap ships. And like smart-bombs (above) it is an AOE weapon so it hits all of the ships in range at the same time.
2. E-war Drones: The drone bay of a Rupture has can have effectively the same ECM strength as a T2 multi-spec ecm mounted on a blackbird. A large Tracking Disruptor drone has the same disruption capability as an unscripted T2 Tracking disruptor. This effectively turns your drone bay into extra mid-slots.
And the Number 1 overpowered item in EVE that almost nobody uses...
1. Destroyers: Take the Agony Wolfpack class if you want to know what these can do!
Retired bonus item: Anything that reduces signature radius. A year ago nobody cared about this, but as Armour HAC fleets have shown recently.... this is a critically important characteristic.
Edit: My point is not for these things to be nerfed, but rather the opposite.... go and try fits with these items.