What has been your greatest SEO Success

I have had two small successes with my websites. Currently I have a 3 or 4 websites making a few(Less than 5) hundred a month.

At one point I had a forum, which I still have, which was doing over 1000 visits per day. It lasted about six weeks and was gone, back to the 2-300 visits per month it gets now. Not a very profitable site, but still something I am glad to have.

I registered an expired domain that for 6 weeks received about 800 visits per day, mostly from Yahoo. The previous owner of the domain seemed to use some black hat techniques that paid off for a short time for me. After the 6 weeks, it was down to 14 mostly type in visits a day. I have tried to get the website un-banned with emails to yahoo and resubmissions with no luck. A very profitable 6 weeks is all that I received out of this site, but it was still the best earning two months that I have had with a site.

Have you had any past successes that you can share? Please comment.