Ten things I do when taking a site over.
In no particular order
1. Changing the Adsense publisher ID, the affiliate program IDs etc. and Google Analytics number
2. Checking if there's a htaccess and what's in it. Sorting out canonical problems, disabling directory listing (I don't want people seeing what files are in the folder) etc
3. Checking for 404, 403 and other error pages and creating them if they don't exist
4. Checking for a robots.txt, running it against a validation program (because it may look alright and still fail). Is there a sitemap?
5. Removing any identification files in root, like the file Google makes you upload for Google webmaster tools verification. Removing any personal files the owner stored
6. Modifying the copyright, contact us, about us and privacy pages. Creating the relevant email addresses and setting up redirects for catchall to a gmail address (gmail is good at dealing with spam)
7. Tweaking the conf files in Apache that control stats retention and log file rotation. Checking other server side activity such as cron jobs
8. Checking for favicon.ico and adding one if necessary
9. Doing a Xenu search for bad links and cleaning them up
10. Changing the TTL on the domain (which I usually reduce when moving sites over)
What do you do?