I tried the free version of this but unfortunately it seemed to have a loophole regarding the users email address. If a user subscribes to your site with CB and you have configured the CB interface not to allow a user to change their email address when it comes to sending out a newsletter the user can follow the update link and change their email in the newsletter subscription without this being reconfirmed as a valid email or updating the users site registration email.

I tried this out but the lack of documentation made it impossible to set up to its full extent with all the additional API's. The captcha is buggy and unintuitive, user has to hit enter after typing captcha not click straight on the button which is strangely named "login" rather than "send". The captcha was also disappointing in comparison to the popular recaptcha which better caters for access issues with both text and audio captures available to the user. The contact name is also displaced by the positioning of the form. The google map is so zoomed in that the terrain could almost be anywhere. This was a great shame as the anti spam intentions seemed admirable. Couldn't see any ability to add custom extra fields but then I couldn't find any documentation which may have helped. To top this the uninstall of the related plugins complained about the removal of some files which always leaves a bad feeling. Would also be better if tabs that are not required because feature is not enabled were hidden. In my opinion not yet ready for distribution especially without documentation. Would have contact support but the buggy captcha I mentioned earlier kept getting stuck on calculating even on their own site.

Great that this is free and I know your aim is for something simple which it is but I found some good and not so good features as follows. Will suit most pretty well so long as you don't mind it being seperate from the core contacts component.

Pros:
The built in recaptcha support was easy to set up as I had already set up a recaptcha account to create my keys.
Prefilling fields for those visitors that are logged in is a nice touch.

Cons:
Not an extension of the existing contacts so you loose the fields from the core contact function.
Reentering contact records rather than being able to link to existing contacts in the core functionality.
Only one custom field.
No google map.
Would be nice to see a distinction between messages sent from a logged in user and one that supplied their own email address. Would also be nice to limit the function of sending copy to self to those that are logged in.