package management - Saving deb files from repositories to a custom location for installing offline

I want to download and save some deb files, and preferably their dependencies, of certain apps, from the repositories (apt-get, aptitude) to a custom location without installing, so that I can install those apps while the machine is off-line. Also I want to know if it is possible to download deb files for a 64 bit machine on a 32 bit machine.

You can save all the deb files with dependencies using the following command

sudo apt-get --download-only install packagename

And the files will be stored under /var/cache/apt/archives

If you need to download Ubuntu packages using another machine or OS, check the desired packages in Synaptic and select File > Generate package download script.
You can download 32 bit and 64 bit packages for offline installation here.

Note:
First run apt-get clean, so that the directory will be empty. then if you want (say) a2ps package and all dependencies, you should type
sudo apt-get --download-only install a2ps.The packages will be stored in /var/cache/apt/archives.You can use this for offline installation.

You can also download packages for offline installation in the below site,
http://packages.ubuntu.com/