I have the cording attchment I bought almost two years ago but have never used at all. The sequin attchment is cool but I'm afraid to buy it because I might end up not using them, just like the cording attchment.

There's also this laser attchment from HIRSCH, but this would be too expensive, I guess. And then Chenille Embroidery might be making a comeback also.
Here's an article from screenweb.com by Harry Bernstein of Hirsch on some add-on decorating techniques:
ScreenWeb | Scoring More Sales With Specialty Garment Decorating