it makes sense but a lot of people already thought at something like that. you can also search for domains with that "www" trick because most internet users write the website adress with "www" in front and a lot of them usually forget to write the "." for example: wwwdigg.com most of these are already taken, but they're good domains to park
i have a few up my sleeve that are for an up and coming site that not many peeps know about worth A LOT imo
In terms of the revenue that you could earn by parking yes. Hundreds of people forget to type in the complete url properly- Nosfer above has given an example. You also need to look at the keyboard ( Most countries do use QWERTY) and analyse the typos that are most likely to occur...
There are bits of software that can predetermine the typos for you. But yet again, you can get into legal trouble with some companies.
Wrong section. We actually have a domain section here on DP: http://forums.digitalpoint.com/forumdisplay.php?f=45
Nobody has mentioned about potential TM issues. You need to check if that name is TMed, otherwise you could have problems down the track.