Some ideas:
Brians Juice Bar & Deli
80 E Lake St
Brian's has pretty good falafel and shwarma... fresh fixins and if you're into the juice thing, definitely one of the better fresh juice selections downtown.
Jaffa Bagels
Illinois Center (Lake/Michigan)
Inside the Illinois center concourse, they have good falafel and nice fresh roasted turkey sandwiches and big ol roast turkey legs.
Some others ideas pulled from
http://www.Lunchintheloop.com :
Haifa Cafe
* 163 N Wells St
(312) 332-0063
* 318 W Adams St
(312) 346-2288
* 19 N Wells St
(312) 214-1144
* 410 S Clark St
(312) 235-9000
Oasis Cafe
21 N Wabash Ave
I have been to Oasis at one point, I believe its back in a store on Jewelers Row. Been awhile tho.