I was curious about Meal Pal, so when they were offering a 50% off promotion, I signed up.
What it is:
You sign up and pay for a plan, either 12 or 20 meals per month/30-day period.
Various eateries in the area offer a Meal Pal special; some of them seem to be the same every day, but most of them offer something different every day. The offerings go "live" the day before at 5:00 p.m, and you have between then and 9:30 a.m. to browse them (by website or app), pre-order your meal and designate a time slot for pick-up (note, though, that some places only offer a limited number and they can sell out). When the time comes, you just walk in, tell them you're there for Meal Pal (some places have a counter with a sign), give them your confirmation code, take your meal and walk out. I felt really smug today when I bypassed a line to order that was at least 15 deep!
The regular price of the 12-meal plan works out to something between $6 and $6.50 dollars. Note that this includes tax, so the price of the actual meal is under $6; the 20-meal plan works out slightly cheaper per meal.
So far, I've been really happy with my options (chicken curry w/rice; pot roast sandwich with house-made potato chips; three-cheese pressed sandwich with a small salad; beef and lamb shawerma); none of the meals appeared to have been scaled down, even though you're paying $2-3 less than the menu price. There's a huge number of places in the SF Financial District (and you can widen your practical lunch radius because you save time ordering and receiving your food). I've even discovered/rediscovered some new places.
The downside is that you can't customize your meal (ask for no mayo on a sandwich, etc.). The vegetarian options are limited.
Of course nothing beats bringing lunch from home. But if you find yourself spending a lot of money buying lunch (which is getting close to $10, at a minimum) at least three times a week, this is worth looking into.