A fast food kebab joint asked me if they could benefit from a website?

I said yes, but I didn't really know how. I'm looking for answers.
They're no Pizza Hut and don't deliver. They're more of the type where you get a kebab on your way home after a night out, but they are open during the day.

I said that it could boost their business if people wanted to order online and pick up (collect), or didn't have a menu to hand and wanted to choose before calling up or walking in. A bit weak really.
Also if they wanted to look up their number before calling in.
I also said that they might want to gather visitors email addresses and put special offers on their site and then email the visitors email addresses that they gathered with a link to the offers. This would kind of remind the customers that they are still there.
Also said that there are other sites that do offers and coupons, that people could search, if they register with them, it would be best to have a website as the customer is obviously already online.

I want to go back to them with something more, any ideas???