I think Walker's Service Center remains in business while they try to sell the building (which to my memory has been on the market for years), but obviously they were not the first tenant here in what was a service station of some sort.
The architecture is distinctive enough that I ought to be able to name it easily, but in the event it's slipping my mind, and I will update the post title when either someone identifies it, or I remember to look it up at the library. These full service gas stations use to be just about the only ones you saw, and with cars so much more fragile in those years, that made sense. Now they are a dying breed, and with the closure of Forest Lake Exxon I can only think of a few left in town.
UPDATE 23 February 2012: Updated post title from "Gas Station" to "Abbot's Texaco" based on the comments.