(duplicate of http://brainstorm.ubuntu.com/idea/6234/)

i do not want to download second time a package[ set] i have downloaded and installed with synaptic.
i know they are stored in cache but novice user does not know about that. i do not know whether they will be stored by ubuntu in that cache in future if there will be little space on the disk. i want that if i want a package from that local storage i can automatically "extract" all dependencies of it if they are there and question to download if it is not there. for example if i want to copy opera package from storage to /home/dinar/files_prepared_to_write_to_cd i should be suggested to copy also Qtlib and i should be able to deselect it from copying. this folder should be in a separate partition and should be mountable to another ubuntu on this computer. and synaptic of another ubuntu after mounting this storage should show packages that are already downloaded[ and are ready to install]. and if i carry(bring) some package files on a cd or flash drive to an ubuntu on another computer and then double-click in it to that *.deb files it should suggest to copy them to its local storage.