I guess this extension is the best download manager at the moment.
But please if you release your extensions in a compressed file don't add the .svn files with it, we don't want and need all that mess on our server, there is a function in SVN where you can export the files in a clean way for release, use it!

Extension looks very promising and very cool but the installation instructions don't look simple to me and the 3th party requirements don't make me happy to.

Not bad but need some improvements.
1 - Try to put in some un-install support, at the moment you can only remove it by force.
2 - Clean up your code a little and get rid of repeating scripts, put them in a function and put that in your helper class and call them as objects.
3 - Take in mind its extremely difficult to download your extensions if people don't understand your website language, don't forget the site were you promoting them on is English.

Good luck!

The guest book is not bad although there are some bugs in the admin section but the Captcha totally don't work, after one week of installing this extension the guest book was loaded with spambot messages and i had to disable it.

What is the point of this extension? it is already a part of J1.5.
Ever tried to login in into Joomla, clicked on "Help" -> "System Info" then click on the "PHP Information" and here you have it. lol