Well, one of my tenants called and said that her bathroom light fixture had fallen on the sink and broke a big chunk out of the basin. UGH! That's a big chunk.

Seeing as how the chunk wasn't really shattered off, just sort of broke off, it fit nicely back into the sink. Off to Home Depot it was. I'm getting more and more familiar with the people there, so I found one of the guys I've used as a reference before (he helped me figure out the pump contraption for the Great Carrie Pumpkin of 2003), and he directed me right to aisle 2 that has the epoxies. He recommended Super Glue Epoxy Adhesive. (explanation of what makes super glue so “super“)

It needs to be mixed before you use it, but the packaging makes it easy, as you just depress the plunger and it squirts out equal amounts of each part. Then, you mix it for about 30 seconds and apply it to both surfaces, the chunk and the sink. The epoxy package said that you could use the plastic package bubble as a mixing tray, so that is what I did. After pushing out a bunch, I mixed it, then applied it to both surfaces. I fitted the chunk back in, held it for a bit, then let it sit for a couple more minutes. After it was seated, I applied some porc-a-filler porcelain chip filler and am waiting for it to set overnight before I sand it. Yeah, it looks like crap right now, but I think it will clean up nicely with a bit of sanding.

Presto! I'm curious to see how it works.
[Update: Here's the final product after a bit of sanding. Not a masterpiece, by any means, but it holds water, and I think the new enamel will fade over time]