why don't you include some more translations in Skype installation? (most popular ones?) installation is big (or not) enough already, and Skype translations are pretty small files.

Actually they are not that small .
What particular translation are you interested in?
Which are the popular ones not included?
Regards,

Croatian/Hrvatski (Bosnia and Herzegovina)

I currently know of no plans to include extra languages i'm affraid, but if there is a translation in the translation forum (and i'm almost certain there is) that surely can be distributed.
Regards,

yes, but how, why, and when?

this translation could use, rough estimation, 20-25 million people.

isn't that wort of including in installation?

I would be worth probably including every language on earth, this isn't the issue. Also number of people speaking the language isn't a determining factor probably cause if it would hindi and swahili would already be included.
I only know that extra language ads extra weight to the installer. Other that this I have no idea based on what it is decided to include a language or not. Most likely the curently included ones were trasnlated quicker and then a number was reached where the installation file size was acceptable, but not too large. But this is my personal guess.
Regards,

g_simic have you translated Skype to Croatian?

yes.

http://forum.skype.com/index.php?showtopic=59256&st=0

Thanks.

No problem.