Twitter clients, only shorten URLs as much as you truly need to and make them readable
I think URL shorteners are are a curse, but thanks to Twitter they are growing vastly in use. If you don't know, URL shorteners are sites that will generate a compact encoded URL for you to turn a very long link into a short one that's easier to cut and paste, and in particular these days, one that fits in the 140 character constraint on Twitter.
I understand the attraction, and not just on twitter. Some sites generate hugely long URLs which fold over many lines if put in text files or entered for display in comments and other locations. The result, though, is that you can no longer determine where the link will take you from the URL. This hurts the UI of the web, and makes it possible to fool people into going to attack sites or Rick Astley videos. Because of this, some better twitter clients re-expand the shortened URLs when displaying on a larger screen.
Anyway, here's an idea for the Twitter clients and URL shorteners, if they must be used. In a tweet, figure out how much room there is to put the compacted URL, and work with a shortener that will let you generate a URL of exactly that length. And if that length has some room, try to put in some elements from the original URL so I can see them. For example, you can probably fit the domain name, especially if you strip off the "www." from it (in the visible part, not in the real URL.) Try to leave as many things that look like real words, and strip things that look like character encoded binary codes and numbers. Of course, in the end you'll need something to make the short URL unique, but not that much. Of course, if there already is a URL created for the target, re-use that.
Google just did its own URL shortener. I'm not quite sure what the motives of URL shortener sites are. While sometimes I see redirects that pause at the intermediate site, nobody wants that and so few ever use such sites. The search engines must have started ignoring URL redirect sites when it comes to pagerank long ago. They take donations and run ads on the pages where people create the tiny URLs, but when it comes to ones used on Twitter, these are almost all automatically generated, so the user never sees the site.