Iframes in website

I am considering using iframes in one of my websites. From researching security issues it seems like the biggest risk they present is when you browse to untrusted sites using iframes.

Am I correct in thinking that there is very little if any additional risk cause by using iframes on my site?

Any iframe related vulnerabilities or other concerns I should be aware of?

Thanks as always for the replys!

Securing Apache Web Server with thawte Digital Certificate
In this guide we examine the importance of Apache-SSL and who needs an SSL certificate. We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.