Easy to integrate open source CMS?

Hi,

We just finished building our website with custom CMS, built specifically for our website. However, the CMS is not really cool nor rich, at least compared to those CMS out there. Now, I am looking for an easy to integrate open source CMS there. One that won't force us to redesign our website [which users visit] or our database [which is totally functional and no problem at all]. I have tried a few but all of them add a lot of tables to the existing database which is really headache and really unwanted for.

I have visited this website:

http://www.cmsreview.com/OpenSource/directory.html

but all seem to be the same. Any ideas please?

If you are interested in building your own CMS try any of these.
http://www.innovastudio.com/editor.aspx
http://tinymce.moxiecode.com/

Both buddypress and Vanilla (Garden) easily integrate into other web sites.Buddypress works best with the Community theme in a WordPress environment . It comes with multiblogs and a forum integration as an option.Vanilla works with Wordpress and Drupal but their integration plugins are rather simple; it s jua matter of settings and pointing them to each other with the correct signin addresses.
Mingle can be used as a forum integrator.Symposium only works with WordPress so far to add a forum. Drupal can also accommodate multiblogs as does b2Evolution.
It would help to know what kind of integration you are looking for to integrate into your existing CMS.