While I dread these on Shiichan (far too in your face there and not really all that useful in threads), I see that they sometimes use it on the bonotto based boards (http://www.bonotto.jp/) but not for threads but front pages. With them you can browse through the thread lists (a new thread list (e.g. 41-80 for this board) gets loaded and the first (10 for this board) threads for that page get listed.
This helps in not having to CTRL F through the subback if you don't feel like it.
On bonotto, they are placed on the very bottom of the front pages.
Just a minor suggestion.
Hmm. Kareha now has paging code that's used in the image board mode, so it wouldn't be too hard to implement, maybe. I shall consider it.