Just thought of a few examples:
Google- when they registered the google.com name, were they focusing on having 'Good English' in their domain name? No, they practically made up that word (although it is similar to a googol)
Veggie Boards- I am a member of this forum too. This is the top forum in this niche and veggie and a shortened version of vegetarian. vegetarianboards.com is much longer and harder to type in than veggie. And there is also a hidden benefit, by abbreviating it to veggie, they are also appealing to vegans at the same time. (thought this one was a great example)
As for shortenings of words like to = 2, the = da and other crap like that it doesen't really appeal to me that much. Infact, I am not a huge fan of numbers in websites, for example, I believe the domain name of retireat21.com is colding the site back.