This plugin makes your shortlinks shorter!
The default WordPress "shortlink" URLs look like
http://www.example.com/blog/?p=123, where "
actually a 7+ digit decimal number. This plugin shrinks your
shortlinks by encoding that number into only 4 characters, and using
the abbreviated URL prefix of your choice.
On my site, the default shortlinks are 35 bytes long, even though I have a very short domain name. This plugin shrinks them to 21 total bytes, which is comparable to most public URL-shortener services, and better than many.
This doesn't affect your (long) permalinks: those can still be in whatever format you like.