Hiya Fico_Focused
When I got my card back in April of 2006, they initially gave me a $2900 limit. After a few months, I requested a $3500 limit and got that. I think it was about 2 maybe 3 weeks later I tried for a $5000 limit but it was denied due to asking for another increase in such a short period of time. However, I waited a bit longer, tried again, and got the $5000 increase. I waited a few more months and asked and got a $7500 increase, and as of about 2 weeks ago, I requested a $10,000 and I got that as well.
I should note I made all these requests through the AMEX website. Hope this helps a bit. 
For those interested, the card is the AMEX Blue Sky. I had an EQ score of about 680-690 when I got it, I believe. My score with EQ as of yesterday is 766. Good luck!
