I must blame Fonso again, because he asks me about something like FlashGot but for Opera in Linux, i.e., a way to be able to select a block of RapidShare URLs to download them with a premium account with a download manager. So when I didn't find anything, I started with it.
I finally got a bash script that receives a list of links as parameters and adds them to Aria with a RapidShare premium account. Using aria was not a choice, since it was the only one, apart from wget, that supports RapidShare premium accounts (i.e., HTTP authentication) without problems.