Like your idea KradenX. Instead of a Kamikaze, more like a Phase ICBM, something that you can only use for one Phase jump, then it auto attacks structures or the planet on the next map. It would have to be built in the system it was fired from.
Another option I'd like would be Monitors. These would be Non phase jump capable Frigates and Cruisers, they would have to stay in the system they were made in (perhaps a new capital ship type could move them, but it would be VERY slow when carrying a Monitor). Monitors would be more effective at combat (faster, more firepower) than other ships their cost, they'd make great defensive ships, but obviously not so good offensive.
Larger Carriers. The current ones just don't seem impressive. How about make Supercarriers that carry twice as many fighters, have flak cannons, and are bigger.
Super Frieghters. These would be cruiser sized ships that would give a bonus to trade and culture in the planet they were stationed at, they would have minimal weaponry (about like a colony ship). Super Miners would be similiar with an obvious role. Both types of ship would be very, very slow.