Langenscheidt Collins Grosswörterburch Englisch (neu!) with 350.000 words and phrases on 2.136 pages!! Plus it's got the thumbholes ("Daumenregister" auf deutsch) so you can find your page quickly. It's big and weighty, a proper reference book (or murder weapon, quick hit to the back of the head would finish any one of my team mates off!) and a bit of treat (cos it was quite expensive...)
I love dictionaries :-)