That purple daisy link didn't work for me, just goes to a blank page.
This is the tip I use.
http://apassionatequilter.blogspot.c...etal-tips.html
I originally bought them from Sharon Schamber, but I've also seen them sold at arts & crafts stores such as Michael's, you can also find them at bow & arrow supply stores (weird?).
The quilter in the link above is correct, you can just screw the tip right onto the end of the Elmer's bottle. She seems to take hers on and off and wash it out between uses, but I found that I could just stick an applique pin in the end as a plug. I use the Elmer's washable school glue.
To answer the original question, I use glue for matching difficult seams, and applique.