Smith Street lunch?
i work from home sometimes, too!
Most of these places aren't new, but thought I'd list them in case you haven't tried them yet:
-Brooklyn Canteen has some great food sandwiches and salads - same owners as Seersucker, I believe.
-Hophap - Thai restaurant that, while certainly not attaining Elmhurst levels of greatness, has affordable lunch specials
-Cubana Cafe also has some decent items
Not on Smith but good:
-Mile End has interesting and delicious sandwiches
-Cobblestone Foods has some great sandwiches, too - love the turkey and the catfish po' boy (it's not trying to be an authentic Louisiana-style replica)
-Ted & Honey - a bit further of a walk to Clinton St, but have nice sandwiches, salads and soups
-Hibino - a walk to Henry st. mainly sushi, salad and cooked specials
-Fisherman's Dawta - they don't seem to have predictable hours but their Jamaican food is great. I also love how they're counter service. Makes lunch less of a pain to get.
-Bar Bruno - might also be a hike since it's on Henry and Union. I've only tried their dinner but perhaps lunch is worth a shot. They also have a takeout window.
-Ferdinando's Focacceria - classic
-Buschenshank - German food or Pizza, woo!
-Van Horn -already mentioned (their fried chicken sandwich is great)
-Defonte's - if you can trek out to Red Hook for a giantic Brooklyn Italian sandwich
BTW, just so people are looking for the right place it's Smith Canteen http://smithcanteen.com/ It can be very good to great. As waxyjax notes, same owners as Seersucker. Only place in the city I've seen serving burgoo. (It was excellent, but sadly served a little lukewarm -- I still devoured it quickly.)