This is a tactic in the books of certain Intel agencies. Disclaimer - it can be used negatively, but if used defensively this can help your company and give side benefits to SEO (betchya the spooks didn't figure that one out!). 

Ok, so we're familiar with the idea of typo-squatting. I'll use one of my sites as an example. When I look on Google Trends or such and see that 25% of my traffic goes to www.airwalks.com rather than www.airwalk.com, I can either take defensive action and register that domain (301 the traffic to my correct site) or the blackhat me would register the domains for my competitors (e.g., Vans) and redirect the traffic from www.van.com to www.airwalk.com.

If I were also blackhat I might register www.googles.com and host AdSense ads on it from Google and just make a few dollars...

But here's the really interesting part - if you work in a highly competitive area or for a government department or a big corporation -- any area in which NDA's, secrets, etc are the norm -- imagine this...

You work for www.bigaerospaceagency.com and get regular emails with "This design honestly didn't come from the UFO in the basement" on them. Now imagine the daft director (there's always one) who doesn't understand the blackberry or has pudgy fingers that misspell all the time.

He types in [email protected] (which has been registered by a competitor, or worse, by conspiracy theorists!) and thus my UFO design is emailed to a typo-squatting domain that doesn't host a page, but simply redirects email... 

Imagine the chaos...

In other words, it's a good way to encourage those corporate security types to register all those misspelled domains from their budget (plus you get all the traffic and links!).