jacatone, do you have premium accounts with megaupload &/or rapidshare?
If so
rapisucker is a good script to use. It needs to be updated to work with megaupload since their site update, but it is actively maintained & so that's not a problem:-
RapidSucker
Another good RS cli downloader for premium users is
Modrapi. I've been using it without incident for quite a long time now.
Modrapi
If you want to download as a free user there are several tools available from
Google Code. Some are commandline scripts that are very easy to use (copy some links to clipboard, type
megaupload-dl -c and the links are autodownloaded, similar script is available for rapidshare). Others have gui's, like
Slimrat.
http://code.google.com/p/megaupload-dl/ - for free MU users with no premium account
http://code.google.com/p/slimrat/ - d/loader with gui, works for file multiple hosts