I have been hired to make suggestions for a site, it is using a .se domain, but the whole site is written in English and is targeting a mostly US market. The web site has been around for almost ten years and have a lot of back links. The site is preforming really well in Yahoo, but is not all that visible for Google users in the USA. I really want to move the site to a .com domain, but I am not sure how to go about without damaging the short term earnings. I might recommend a gradual move or even a mash, but both strategies must be used with care. A full HTTP 301, redirect would be to dangerous. Building a brand new site at the .com and getting fresh links for it, waiting a year or so before a gradual move from the old site might be the safest, but it would increase the cost of the move. To make matters worse the .com is dirty, it was prevolsy owned by another firm in a related industry.