Here is an old-school dictionary which is still often seen in bookstores in Egypt. It was probably the best of its kind for some 70 years, until Badawy and Hinds produced their dictionary of the Egyptian colloquial.

I won't be harsh on dear ol' Spiro, because it's still a decent dictionary and it's good to have it. It includes a lot of vocabulary which you need if you're interested in Ottoman Egyptian history or Egyptian material culture (clothing, traditional kitchen utensils, etc). The scan which I found is actually decent (but not great) once you get past the few first pages.

Here are the problems: I like dictionaries with sample sentences, and it doesn't really provide many of them. Also, it doesn't tell you when to drop your qaf, which is quite important in Cairene Egyptian. So, to take a really simple example: kwayyis 'awi is represented as kuwayjis qawy, and you have to look it up under qaf-waw-ya, as you would in Wehr or most other Arabic dictionaries.

So, if you are already somewhat comfortable with written Arabic, you can use this one. If you're starting from scratch, you should still get it, but accept that the written form may not make sense for you until later, and perhaps supplement it with something lighter and more touristy in Latin script.

NB: I bought Badawy and Hinds, but I don't have it physically available these days, and it's relatively large and painful to scan, while you can buy it for cheap in Egypt. If someone does submit to that labor, however, I'll be completely awed.

Finally, if it hadn't been for YOZ, I would not have remembered to look for this dictionary, so, please thank him (?) as well.

Arabic (Dialect)