Well, as I was typing this up, it looks like Kipp beat me to some of the recommendations, but I figure I'll post this anyway, since there's a few he didn't have listed.
I have a somewhat unique perspective, since I live here, but here's what I like (that aren't big chain places) broken down by style:
American:
Chubby's - where the old Phoenix Records was after they moved off the square (W. Adams, a couple blocks east of campus). Chubby's does Chicago-style food, italian beef, hot dogs, etc., but they also have an amazing horseshoe (especially the buffalo chicken one). I've heard complaints from other people about the service, but personally, I've never had any problems.
Jackson Street Pub - on west Jackson, same place it's been for decades. Hasn't changed..still a dark "hole in the wall" kinda place with great food. Also has a great horseshoe (try the tenderloin horseshoe). Just be aware that they don't accept credit cards...cash or check only.
Rocky's - west Jackson, where the old Regulator bar was (if it's been a while since you've been back)...but now painted purple. Sandwiches, burgers, the usual "sports bar" kinda stuff. Personally, I'm a fan of their Reuben sandwich.
Sports Corner @124 - right across the street from the southeast corner of Chandler Park. I haven't eaten here much, but when I have, it's been good.
Chick's - on the south side of the square. The specialty...chicken lips (kinda like long chicken strips covered in a somewhat different take on traditional Buffalo sauce). You can have them by themselves, in a sandwich, baked potato, pizza, salad, nachos, and my personal favorite, in a wrap.
Old Dairy - just off the square to the south, across the street from the public library. They've got great sandwiches, a large selection of desserts (pies, cakes, etc.), ice cream and coffee. A great place for a relaxing lunch.
Pizza/Italian:
Unfortunately, I can't speak much about the italian food in Macomb, since it generally disagrees with me. But, here's what I do know.
Larry A's Pizza - east Jackson, across from the K-Mart/CVS area. Larry A is Larry Aurelio...a member of the Aurelio family that started the Aurelio's Pizza chain. I don't know the full story, but Larry started and ran the Aurelio's location in Macomb after he had attended Western. At one point, many of the locations were sold/converted to franchise locations, and Larry was essentially forced out of the business. So, he took the original Aurelio family recipe and opened Larry A's Pizza. I've heard many people say that this is by far the best pizza in the area.
Italian Express - west Jackson, next to Dairy Queen. great subs, pasta, italian breads
Palermo Pizza and Subs - west Jackson, out more towards the edge of town. haven't eaten here, but I've heard from a lot of people that the sandwiches are amazing. so much so that when they used to be located in Colchester, college kids would carpool the 15 minute drive out to Colchester just to eat there.
Mexican:
El Rancherito - fast service, decent mexican food. a fairly standard, but good, mexican restauraunt.
Guadalajara - in the old Hardees on east Jackson...in front of K-Mart. Similar to El Rancherito, I've only eaten here a few times, but it's always been good.
Chinese:
Asian Buffet - next to k-mart, recent remodel and name change (can't remember the new name, but it's similar). Good chinese buffet, recently added "Mongolian Grill" type service too.
Yummy Chen's - formerly Yen Ching on west Jackson. remodeled, changed ownership and names. Just recently reopened in the last month. I haven't eaten here yet but I've heard it's pretty good.
The slightly "higher-end" places (this is still Macomb, there's not going to be Chicago-level "high end" here):
Red Ox - West Jackson. Known for their steaks and seafood.
Magnolia's - Just off the square, diagonally across from southwest corner of Chandler Park. Southern-style cuisine...seafood, cajun-style entrees, etc. I've been to Savannah and Tybee Island, GA twice, and this is on-par with some of the better restaurants down there. You want some cajun pasta or southeastern coastal style chicken or fish, finished off with an excellent slice of Key Lime pie while sippin' on a Mint Julep or a glass of wine....this is your place.
Ice Cream:
FYI Self-serve frozen yogurt - across from south side of Chandler Park. Your standard frozen yogurt type place, pick your flavor(s), toppings, syrups/sauces, and then pay by weight.
Dairy Queen - ok, so this is the one place that is a big chain, but Macomb's is one of the oldest Dairy Queen locations, is a a staple of the midwestern small town, and
was once owned by my great great uncle, Gilbert Stein. Since they're an "outdoor" store, they're only open from March through early October though, so if you're in town during the late fall or winter, it's not really an option.