AptUrl
The apturl is a graphical mini-program for installing packages from the repository that as user has. Firefox and Pidgin programs come with support for it,
Making an APT link
Single package
The basic syntax for an apt link is the following:
<a href="apt:package">click</a>
Where package is the package you'd like the user to install.
Multiple packages
To bundle several packages into one link, the syntax is the following:
<a href="apt:package1;apt:package2;apt:package3">click</a>
Where package1, package2 and package3 are the packages you'd like the user to install.
AptURL uses
Appnr.com is a website that works entirely on apturl links.
Apturl links can also be very handy if your program is available in Ubuntu repositories. Providing one on your project website is a user-friendly way to have the user install your program and additionally takes the load off your servers.