How about MyAnimeList onebox? It's a comprehensive source of all important information on any anime including:
- User rating (very reliable, most recomend MAL for anime ratings, like IMDB for movies)
- Genre (more accurate than Wikipedia)
- Episode number and length
- Related works (sequels, prequels, spinoffs, adaptations, etc)
- User recommendations
Let's take Flag anime as a not so obvious example. Currently a Wikipedia onebox of it looks like this:
MAL onebox could look something like this:
The title of such onebox would include the English official title and the Japanese original title in parentheses, followed by media type (TV anime, movie, OVA, ONA, manga, novel, one-shot).
Subtitle would contain User Rating, as one of the most important bits of info, followed by episode count and length, and end with genres.
The body of onebox would contain plot synopsis.
There are two types of links for every anime title:
And similarly for manga:
MyAnimeList also has an accessible API with documentation that SE could make use of.
This is just a sketch, so if you have a better idea of how to use the limited onebox space, please post your own version!