I just started thinking of how many skills are available in the limited sense in game and I don't think I've seen any real list, only individual posts about specific skills. I'm going to list skills I can think of that are either broken or need to be seriously looked at to make them viable. I'm not sure of how to change all of the ones I'm listing, I'm just listing what I think and that might include a suggestion on how to make it useful / fix the skill. Please try to limit any additions to skills that are seriously broken or so pointless the only reason you'd use them is to mock your enemy. I'm also only posting about Engineer class players because that's what I've used most.
Boarding Party - three, small flying ships that are shot down very easily and take damage from someone looking in their direction (ok maybe not the last part). Why not beam over when facing shield drops? The Borg do it regardless of shield so the mechanic must be there.
Nadion Inversion - it has a purpose but it is short lasting with a 10 minute timer on use. Only Engineers have two separate skills that have a 10 minute, or longer, cooldown.. It might be more useful if the timer was 2 - 3 minutes. 10 minutes if far too long.
Quantum Mortar - takes an aeon to fire, just as long for the shot to land, never seen it useful in game.
Transphasic Bomb - for a bomb it has almost no damage. Is it a bomb? I've fallen over rocks for more damage.
Orbital Bombardment: Like a single-shot Quantum Mortar, but even less useful.
Tactical Initiative (Space Version): In an Escort tac skills are most likely jammed up against system cooldowns , while on a non-Escort it only affects 2 or 3 skills. (Ground version is nastily useful though)
the space version of tactical initiative is amazing, it lets you solochain your dps skills for about a minute which results in much, much higher dps. I would gladly swap out nadion inversion for the engineering team equivilant of tactical initiative.