For letter "J" --
Jame'Asr Hassanil Bolkiah Mosque is the largest mosque in Brunei. It is know locally as Kiarong Mosque. Impressive on the outside with its golden domes, I've read that the interior is even more jaw-dropping.
This is another postcard that I couldn't caption. It was hand-delivered by the same friend who gave me the Cambodia postcards that were featured for letters A, B, and C.