How about any of the following:
* New weapon- "Meson Blaster" (MB): this weapon penetrates through the titan and may damage multiple locations. It does 1 damage to the external armor on its way in, PLUS 1 damage to all internal locations that the energy beam strikes though, PLUS 1 damage on its way out. By the way, it has a 10% chance (per body part) to damage an internal system when it strikes through the internal structure.
For example, you hover over an enemy titan and fire the MB. Suppose that the energy beam enters through the head and exits through the right leg. The enemy titan gets 2 damage on the head (1 ext, 1 int), 1 in the RT (int), 1 in the LOT (int), and 2 in the RL (1 int, 1 ext). I know this may be very hard to implement, but again, it's a crazy idea
* "Meson machine gun" (MMG): 1.0 ton, 1 slot, 4 heat, reload in 8 secs, +5% hit mod, and does 1 damage + 1 internal damage. Can fire two shots like an MG at range 0 and has a 20% chance of doing internal system damage.
* Long range NMs with a -15% chance to hit penalty.
* New weapon- "Heat ray" (HR): basically it heats the enemy up using sheer energy, not ammo. The amount of heat done to the enemy titan also decreases with range. And an added bonus: if the enemy is already in heat red or heat white, hitting it with one of these will require it to perform a DCS skill check immediately (with a slight penalty on the location hit by the HR).
* New weapon- "Hydro Guass Cannon" (HGC): Like the GC, except that it fires a concentrated beam of water. It requires 2 PU to fire and you can reload more ammo if immersed (-1~-3m water only; you can't reload in swamp, lava, or acid

)
* New weapon- GME 2 Rack (it should take 4/5 slots for game balance)
* New CC weapon- "Sledge Hammer" (SH): 8.0 ton, 3 slots, 10 heat, 12 PUs to reload, -10% hit mod, and does 5 external damage. It also increases instability by 80%. However, if you miss, you have to make a piloting skill check similar to a missed kick.
* When a titan is hit by a CLG, its heat should drop by random(5) degrees.
* When an NM rack or flamethrower attacks a hex with frozen water, the ice should melt. If a titan is on it, it has to make a piloting skill check.
* Titans should be able to drop to the prone position voluntarily (requires a skill check- if it passes, there is no falling damage).
* Titans should be able to turn in air using 20-25% JMT.
* And finally, recon titans should be able to swim in -3m water when prone
