Thanks, guys. All very good points indeed. I agree that the frame may well be suffering from more unseen stresses and may even fracture again at other points. I was planning on selling the frame and was only able to get about $500, when I found the crack right before meeting the buyer. Naturally, I had to tell him and of course he no longer wanted it. So, to spend $200 on a frame that was only going to sell for $500! Makes no sense.
Welding at this point is the best economical option if I'm going to use the frame at all. I was going to weld, then build it back up as a second, cheapie, thrasher bike. I usually ride rocky, high speed trails such as Santa Teresa, which is probably what lead to the frame's demise. If I build it back up again, I won't be doing speed runs with it down Styles or Rocky Ridge, just mellow stuff or even for the road.
If I don't weld or fix it, it will just continue to hang unused like it has for the past two years. So it might as well use it for something....