First of all, I am a persuaded admirer of Adminer :)
I have an idea of how to make it more powerful. Imagine table `User` and table `Photo` which has a foreign key column `UserID`. When viewing table `Photo` id's in column `UserID` appear as links (href of them is to `User` table selecting particular row). It's convenient, but I think that if we could observe this row in pop-up (without clicking) would be even more incredible. So, hover cursor over foreign ID - a popup appears with foreign row properties, click - the behavior is the same. It could be another killing feature.