Hello frosticek
I've found this free open source awesome carousel slider
http://owlgraphic.com/owlcarousel/

it has many feature and effects and is more flexible than the slider for osclass if you you can embed it in your theme it will be awesome

also if you can made the theme show latest items in each category not only in all the website it will be useful specially for premium items and may be they can scroll through a slider based on the above plugin

@crymatisticos
1) OSC Slider plugin is not our, so we do not plan to update it with different script
2) I would be possible to show latest listings for each category, however such page would look like eCommerce, not classifieds.