Is it possible to clone only the software installed on a machine? Obviously in order to copy it to an identical machine that doesn't have the software installed.
On Linux, it's easy to keep a record of installed software and restore it later. Details vary depending on what type of Linux, but generally look like this:
On Debian and Ubuntu the backup command would be:
dpkg –get-selections > installed-software.log
and restore would be:
dpkg –set-selections < installed-software.log apt-get dselect-upgrade
The best part about this is that it's very fast & a very small file, because you're saving only the references to what you have installed. Your Linux repository does all the work of actually saving the programs. Yes, you have to pull these packages off the network, but speed and simplicity are worth it.
Note: This only backs up the applications, not any user settings or config file changes, etc.
As per the comments about Ghost - I find Acronis True Image to be the best imaging tools for windows. With the latest version if you get the Plus Pack you can restore an image to non-identical hardware too. AFAIK though it is a full image including the windows/OS installation too - don't think you can do just the software
With Windows, I'd say it'd be impossible to copy every piece of software given the different permutations of file locations, registry entries, registration and anti-piracy mechanisms. Ultimately, it would be too much work.
So, I agree with @Zsub, just clone the hard disk. Even if the system isn't that similar, you haven't lost anything by trying it.
I realise the following might not be much use now, but to save this work in future, you could use portable apps (e.g. PortableApps, The Portable Freeware Collection) where possible and install only the software that needs to be properly installed. Moving to another machine should be quicker and easier. This has saved me lots of time in the past. Quite a lot of software just works too when you copy it (albeit dumping registry entries etc.)
You could take this one step further and place all the portable apps into DropBox too.
There are several applications available that purport to do this, among them PickMeApp (beta, versatile, InstallMonetizer), PCMover (Commercial, from LapLink) and ZInstall (Commercial). All have different levels of support for range of applications, different price points, etc.
I have not significantly tested any of them, so I'm not going to specifically link to or recommend any.
PickMeApp is the only one I've tried since I was hoping to move a circa-2007 software package from an old system, and it was unable to pick up the somewhat-specialized package I was looking to move. In addition, PickMeApp "offers" to install assorted software with dialogs that in some cases don't even have visible Decline buttons. It does this both when you first install it (e.g. to a flash drive) and when you run it on a PC from which you're hoping to clone a program; I don't know if it does so on installation as well. Recommended only for use by IT pros who know what to expect, and then possibly only as a desperation move.