A bit of a drive from Magog but Knowlton has some fun eateries. I would recommend staying away from L'Auberge Le Relais though. Ate there a few weeks ago and it was dismal - at best. Great service, but food - not so good. I mean they ruined duck. It's the townships - don't ruin duck!
La Table Tourigny (4288 chemin Georgeville, 819 868-2894), located 14 km south of town, used to be great for dinner but their website is down and Google doesn't turn up any recent references. Still, you might try calling.
If you don't mind travelling to lovely North Hatley, there's Café Massawippi. www.cafemassawippi.com
In the FWIW department, someone on that other board has raved about the newly opened Auguste in Sherbrooke. www.dannystpierre.com/auguste/index.html
Also in Sherbrooke, Le Bouchon and La Table du Chef -- www.lebouchon.ca and www.latableduchef.ca -- get good press. Both were founded by chefs from the excellent Auberge Hatley after it was destroyed in a fire.
Isn't Owl's Bread in Mansonville, on the way to Owl's Head? Unless they have another location in Magog, that would be quite the drive - at least 40 km (although probably worth it). I had lunch at Owl's Bread this past winter and we enjoyed it thoroughly. I had some lovely duck sausage with crisp grilled vegetables, and she had an excellent & hearty cassoulet. Both came with a salad and we splurged on a succulent tarte tatin. The portion was generous enough for two, and it wasn't overly sweet - just right.
The service was decent on the resto side, but on the bakery counter side (where you can get many pastries & desserts to go), you may have a chance to engage the charismatic owner in conversation.
We went for brunch at this small place on rue Principal. They had the best french toast made with baguette. It was very cute inside all made of wood. It was right across from the main park area where they sometimes have tents up in the summer. When I look at my pictures I can see the address is around 400 rue principale. Sorry I cant remember the name but it was great.
In Georgeville, about a 20 minute drive from Magog, is Maison McGowan. It is an old waterfront inn with a restaurant. The food tried hard but it is just OK. The setting, however, is the main reason to go there. Lovely waterfront terrasse, beautiful for a sunset dinner in good weather. Not particularly expensive. On the way there you will pass La Table Tourigny, so let us know if it is still open if you go there! I was hoping to go this summer, but not if it is closed.
In addition to those already mentioned, one place I love stopping in at it Caffucino in Magog. It is on the main street of restaurants and boutiques (rue Principale). It is basically what I wish Art Java or Java U were here - great coffees, cakes for dessert, and a great casual menu - paninis, meal salads, thin-crust pizzas (not sure these are still there but they used to be).
If you feel like taking a small drive through the country (or by highway too), in the town of Stansted there is the most amazing bakery called La feuillantine. It is operated by a young family from (France, or are they Belgian?) and their bread, croissants, cakes, fruit mousse cakes I dream about... basically anything I've ever had from there... is outstanding. There are literally lineups out the front door on Saturday mornings and if you show up too late, many items are sold out, since weekenders from all around stock up. Apparently this is the last summer they will be operating (per my mom who chats up everyone, everywhere), so get there while you can! They also have sandwiches and such. It's probably about 15-20 mins from Magog on the highway, more if you go along the lake (and greatly increase your likelihood of getting lost, although you'd gain in scenery).
http://www.lafeuillantine.net/# (check their hours)
This one restaurant is wonderful.
Cavallinis', il ristorante
101 Du Moulin,
Magog QC, J1X 4A1
The food is so well prepared, so full of flavors, it is food as it's best,
an italian gem way out there and I am so returning this summer.
I got you the phone number because a reservation is needed for the weekend, the place gets packed and not for nothing.
Enjoy you time in Magog, it is a beautiful place!