Any statistics out there on commonly mistyped keys?

I actually had to look into a similar issue a couple of years ago. When i began the project i had no idea where to begin, so hopefully i can save you an anyone else in the same situation, some time.

Bottom line is that you can take advantage of a large amount of work done in other fields. The most important of these fields, i found, is Domain Name Registration.

For instance, the Site DomainTools has a 'Domain Typo Generator', which works by generating a list of typo domain names, based on a parent domain name that your enter.

Given that professional domain name owners (aks squatters) account for a large portion of any Registrar's business, it's easy to see who this tool is intended for (i.e., squatters are interested in acquiring common typos of high-traffic domain names--even a 2% error rate for a high-traffic domain name is a lot of traffic to a typo domain name.

In addition, i would recommend the remarkably comprehensive 2005 Study of this issue by Microsoft Research.

Finally, there's a key concept in computational linguistics derived from the Levenshtein Distance, called Damerau-Levenshtein distance, which extends the basic Levenshtein's basic idea of edit distance to the particular problem of humans typing on a keyboard.

The principal conclusion from his 1964 research paper was that 80% of all typos can be described by one of just four operations--insertion, deletion, substitution of a single character, or transposition of two characters.

Damerau not only distinguished these four edit operations but also stated that they correspond to more than 80% of all human misspellings. (The only link i supplied for D-L is the Wikipedia article; i did so because i think this is an exellent and brief introduction plus it contains pseudo-code for the D-L algorithm, and finally the article provides links the primary online sources for D-L.

Most mistyped key on my iPhone/Touch:

c for f! "Cred clies crom Crance to Cinland on Cridays!"

Also, Space Bar for any of the letters in bottom row of iPhone keyboard:

"Bob liste s to Z Top a d an Hale ."