Star Trek Online. You equip a kit and you're good to go. Despite that, they're also rather limited, as there are a limited number of different kit types and each kit of a given type contains a very set number of abilities. Season 9 is thus deploying an extensive overhaul of the kit system, allowing players to build the sorts of kits that they want to use in a more flexible framework.
The core of the system is simple. Abilities are split into two categories for each profession: Assault and Strategic for Tactical, Medical and Research for Science, and Fabrication and Mechanic for Engineering. Kits will become frameworks that contain skill bonuses as well as slots to equip abilities, with each slot allowing any skill within a given category. For more details on how the new kits can be acquired and how the flexibility will benefit players, take a look at the full development blog.