"He likes Tranformers, Lego and Superheroes." So, yeah, that's going to be a tough one.
In order to achieve this mighty quest, we went on Friday to our local toy store, which is less than ten minutes' walk from the flat. Once there, I proceeded to pick out the thing that most screamed out to my inner child to buy. Strictly speaking, there was a need to look out for something fitting the theme, but given that Transformers, Lego, and Superheroes are all inherently awesome, that's not so much a limitation as just a given.
Frankly, the only difficulty is choosing which of the three to get. And even that's less difficult than it seems: you can now get superhero-themed Lego (both DC and Marvel, which is even more awesome), and near-Lego Transformers.
The only problem is that modern Lego is just too awesome. Lego "Star Wars", Lego "Pirates of the Caribbean", Lego superheroes, Lego "Lord of the Rings"... It's a good thing they also put maximum ages on the box, or I could have spent a fortune in there!
Oh, and finally: Happy Birthday nephew #1!