I think the vertical ellipsis glyph (⋮) is underused, so I bound it to ⌥, for easy insertion. This binding is analogous to ⌥. producing the horizontal ellipsis (…) as is the case on my MacBook.

This is achieved just like these multi-stroke key bindings, but with this key-value pair in the top-level dictionary:

"~,"    = ("insertText:", "\U22EE");

Like the multi-stroke key bindings, this binding only works in Cocoa applications.

As to what it's good for:

1. Bind ⋮ to ⌥,. ⋮
2. Profit!