I would like to see a new vessel, possibly of the new corvette class, that specializes in sending boarding parties to enemy corvettes, frigates and cruisers in order to forcibly take them over for your use.
It could work out something like this:
The vessel's primary goal is to rendezvous with enemy corvettes, frigates and cruisers, attach themselves to the hulls of each vessel, spend a few moments cutting through the hull (allowing enemy some time destroy the "leech"), and send in a boarding party to take over the ship.
Once this is action is completed successfully, the boarding corvette is scuttled and in return you have a new corvette/frigate/cruiser.
The time it would take to successfully board a vessel would vary based off of the targets size. Corvettes would take a few moments to break into, where a cruiser's thick armor would take much more time.
The vessel would be extremely fast, and cheap, but would be relatively weak and aside from its hull, armor and shields, defenseless.
When I say weak, I mean it would be suicide to send these against a 700 supply fleet, but it would be strong enough and swift enough to be able to last long enough to be usable early game.
These corvettes would be extremely powerful early game, allowing a player to take over neutral ships around a new planet, bolstering your forces early on, and they would be extremely effective when used in swarms to take over a purely light frigate attack force, but as the game progressed, it would become easier to counter these corvette swarms.
However it would be foolish to say these are purely early game craft, as these cheap and swift craft can wreak havoc on a group of unprotected LRM and Support cruisers that the enemy "tactically" positioned away from the main battle. An unobservant opponent would pay dearly from these.
Upgrades could include speed boosts, faster hull cutting rates, or even stealth that would be countered by scout frigates.