As far as I know, you can still get an IUD if you have had clamydia in the past, as long as it has been cured. I myself just had an IUD insterted about 1 month ago at Planned Parenthood. The nurse did tell me that if someone has ever had PID, they can never get an IUD...something about the scarring and damage from PID. So, maybe, if there is damage left over from the clamydia infection, that could prevent you from having an IUD, but I'm not sure. I know that clamydia can cause scar tissue and such, because my boyfriend was diagnosed with clamydia when he was 15, and he has permanent scarring and damage to his urethra, resulting in some urinary problems.
That being said, I highly recommend the IUD. I have only had it for a little over a month, but it went very well, and I am happy with it so far...only mild cramping and spotting for the first 2 weeks.