Is there a module for showing only posts in some defined date? I would like to make a calendar addon for my website, which would look something similiar to http://www.nikerigarun.lv/ this (scroll it a bit downwards, on the right side). The funcionality would be to show only posts from some selected date, is there such a module for that and if there is, could you please recommend me one?
This is done with the Views module. Create a new view of content with a display type of 'block', and set it up as an unformatted list of teasers with links, then click 'Continue and edit'.

Add a filter on Content:Posted Day, and choose your conditions like 'is greater than' 'offset' '-10 days'.

You can then set any other views parameters to get what you want.

Save your view and go to admin/structure/block to find your block and place it where you want it.