If you liked
UFO Princess Valkyrie
|
...then you might like
Shinkyoku Soukai Polyphonica Crimson S
|
A chibi/younger version of the female protagonist is bonded to the male lead and only in special circumstances changes back to their original forms.
If you liked
Blood+
|
...then you might like
Vampire Knight
|
Both share a similar female/male lead that must dance around the concept of immortality and vampirism in their exploration of each others' feelings.
If you liked
Ayashi no Ceres
|
...then you might like
Blood+
|
Similar sort of framework (female lead, special powers, hopes to help others from an evil she indirectly causes because of her lineage), but I preferred Blood+ on almost every front to Ayashi.
If you liked
Tenkuu no Shiro Laputa
|
...then you might like
Giniro no Kami no Agito
|
Similar main characters and forced separation because of a higher conspiracy.
If you liked
Seikai no Monshou
|
...then you might like
Nishi no Yoki Majo: Astraea Testament
|
A similar thrust into a political battle and into nobility that the main characters in both of these animes experience.
If you liked
Kidou Senshi Gundam SEED
|
...then you might like
Seikai no Senki
|
Very similar space battles and conflict between two races of humans (one genetically enhanced and one not).
If you liked
Seikai no Monshou
|
...then you might like
Tenkuu no Shiro Laputa
|
While much of the story and setting differ, I found the "innocent" feel of the adventure of Jinto and Lafia to be very similar to the adventure found in Castle in the Sky.