Are such books, in Greek, available to buy on the internet?  If they exist, what do the Greeks call them?

I wouldn't mind having a word-search book to hand, when I have the odd bored moment (for example waiting in a doctor's surgery).  I feel that it would increase my vocabulary very quickly.  I guess they would act as "flashcards" because the different word-seaches are grouped into themes, so the words are all connected by that theme.  My wife enjoys doing word-seaches when there's nothing much to watch on the TV.

Any advice would be appreciated.