Isn't that the Grenade Ring your talking about? Either way, it has the same effect.
Except Grenades don't look similar enough to collectable rings to be mistaken for one. I believe the point was to have a damaging ring that could be hidden amongst normal rings and end up hurting someone who doesn't adequetly check them. I wouldn't mind seeing them as a map-specific weapon ring, but even I have to admit it still has the potential to cause problems (patience in a speed-based game? Blasphemy!)
Umm, anyway. Even more refinement of my previous ideas, plus maybe a new one or two:
High Jump: Enhances your normal jump height by a specified amount, allowing the character to break the normal height cap.
Cons - cannot be used in conjunction with a midair ability (spinmoves are still okay though). Jump height is still capped, at 2x the normal one.
Grapple: Fires a non-damaging projectile diagonally upwards. If it hits something, the player is dragged upward towards the impact point, and momentum can be maintained by releasing beforehand. If the projectile hits another player, be it friend or foe, the projectile capechases the target and the player constantly tags along with it.
Cons - fairly short range (grapple projectile disappears after a set distance), virtually useless in wide open areas (nothing to grapple onto, save for a lucky player shot), difficult to control without practice. Cannot be used multiple times in midair unless there is a successful grapple between each of them.
Pinball: Bounces off walls and floors, proportional to your momentum. Activating the move higher up will make you bounce higher, whereas kicking it in whilst moving faster will back you bounce off walls faster.
Cons - you lose control of your character until you deactivate the move, apon which you revert to falling state (as if you just hit a spring), leaving you vulnerable. For better or worse, the move as a whole is extremely unpredictable and is just as likely to kill you as it is to help you.
Swoop: Flies the character forwards in a single down-up pattern, covering lateral distance overall. If the player is about to hit the ground, he will swoop upwards earlier than normal. Can potentially be useful as a fake-out move when being pursued.
Cons - Requires height to be most useful (lower heights lessen overall distance covered), potentially suicidal for covering certain death pits and hazards
Lunge: Unleashes a quick spindash-esque attack that does not need to be charged, and does not require the player to be stationary to use. Reverts the player to standard running state after use. Can be used as a quick redirection for negotiating tight turns. Speed during and immediately after the attack can be altered per character. Handy for traditional melee attacks (because let's face it, 0 speed spindashes suck).
Cons - still slower overall than a spindash. Robs player of control in mid-lunge, potentially resulting in plunging into another hazard without practice.
Teleport: Charges exactly like a spindash, but instead teleports the player directly forwards proportional to the amount of charge the player stores first. The destination is marked by a thok graphic during charging, gradually moving outwards the more charge is gathered. Any monitors and destructible walls (and in co-op, badniks) between the player and the destination are destroyed when the teleport is commenced.
Cons - The thok graphic marker is visible to other players, allowing them to anticipate a teleporting opponent and ambush them accordingly. Players do not carry any momentum after teleporting. Players cannot roll, cannot destroy badniks and such whilst charging (unlike the spindash), and must come to a complete stop to use the ability. Cannot be used to gain vertical ground.
First Aid: Summons a 10-ring box in front of the player. Intended for allies in team-based gametypes. Thrown red rings also replenish the ring count of others if it hits an ally instead of an enemy.
Cons - comes out of the player's own ring count. Enemies can still pop the box and take the contents for themselves. Does not respawn (naturally). Allies do not receive bonuses from special weapon rings. The player loses the ability to roll in exchange for this one.
Directional Thok: Works exactly the same as the standard thok, only the player travels in the direction of the crosshair in FPS mode instead of straight ahead. Can be used to gain height or hit the ground quickly.
Cons - less useful in a firefight than the thok (requires you to aim your weapon and the thok at the same time). Loss of precision in chasecam mode. Most other pros and cons of the standard thok still apply.
Illusion: The player makes a short dash forward, becoming briefely invisible and for the short duration of the move leaves behind a temporary decoy behind that can be destroyed by attacks. Executed similarly to the previous Lunge move.
Cons - unlike the Lunge, the move cannot be used repeatedly, and brings the player to a complete stop after use. The player can still be harmed whilst invisible. All other cons of the Lunge apply.
Zeeky Boogy Doog: Spawns an instant-kill apocalypse shield explosion at the location of every player on the map. You automatically win the game.
Cons - everyone gets sick of it and leaves the server, leaving you nobody left to pwn. Is an obvious joke ability that I don't expect anyone to take seriously.