Salut,
There are really a lot for the STTNG, but all is a question of taste (I have removed some from mine when I got it, as they were hiding important parts from the playfield (there were some character figures and an Enterprise)).
The STTNG is already packed.
illuminated Backplex, decals for the sides, target decals, lights in the ship models and there is a really nice borg mod (but quite expensive) for example.
You could search for these with google or on ebay.
Cheers,
flugs