Our main site is a three word domain. The first two words are the product name (it's a two word product like "search engine" i.e. without both words neither can convey the product correctly) and the third word is the industry. So our domain would be, for example:
(that looks like a new religion!) Anyway, the problem being that more than 30% of people mis-spell "search" and more than 20% type in the two word product as one word so we felt we had to buy:
to be safe ... but throw in an extra well used term for widgetology plus extra tlds like .org, .net, .co.uk, .org.uk and we've ended up buying 63 domains.
Now, logically, 301ing them to the main website is the best thing for our users - yes?
How does 301ing 63 domains to another site sit with Google do you think? We had a problem with virtual hosting on our server so all 63 are on one IP address pointing to our main site on another IP address.
I know that many large sites have a lot of mispellings etc. redirecting to their main site ... but we don't have a direct phone number for Google should they penalise us!
These are all typo domains that have no history? Then there is no problem.
Do you know how long it took me to just check 63 domains history!?! ;)
A few seem to have been parked domains with those keyword pages. A couple used to be sites a few years back, but look like they were genuine sites. The others were not registered before I registered them.
I know of a site that has 1300 domains that 301 to it - almost all were acquired for trademark protection and typo-squatting protection, with just a few that represent businesses that they acquired along the way. That company has not had a problem.
However - problems can come up with lots of 301 domains if you try to get "cute" and use them to leverage your rankings with any kind of "creative scheme". That could include heavily promoting (getting backlinks for) a domain after you have already redirected it. The rule I suggest following is to put the 301 in place and then just let it alone.