The Debian GNU/Linux distribution consists of tens of thousands of software packages. To make sure the packages work correctly together only approved members of the Debian project (Debian Developers and Debian Maintainers) are granted the permission to upload software packages. But there are way more packages than available maintainers. So a large number of packages is maintained by non-official developers. How do they get their work into Debian when they are not allowed to upload their own packages directly? By means of a process called sponsorship. Sponsorship means that a Debian Developer uploads the package on behalf of the actual maintainer. The Debian Developer will also check the package for technical correctness and help the maintainer to improve the package if necessary. Therefore the sponsor is sometimes also called a mentor.
When I started using Debian in 2002 there was a large gap between the number of maintainers who needed sponsorship and the number of developers who were willing to sponsor packages. Let's be honest: sponsoring other people's packages is tedious and sometimes it's easier to just do it yourself. And finding a sponsor was a matter of submitting an RFS ("request for sponsorship") to the debian-mentors mailing list. Only few developers followed that list. So I came up with the idea to provide a user-friendly web-based package repository where sponsors would upload their package and expose them to the public. It took half a year until I understood package repositories and the gory formal details of Debian packages good enough that I had a Perl-CGI-based web site ready. So in March 2003 mentors.debian.net was officially going live and increasingly many package maintainer uploaded packages.
To deal with several feature requests the crappy old Perl code was rewritten from scratch and then years later rewritten from scratch again in Python. But the popularity grew and ideas kept coming in. Finally it become clear that a more generic web application would be needed. And it was more than what I could work on in my spare time. At the same time I was invited to become a mentor during the Google Summer of Code in 2008. What a coincidence. So I advertised the project of rewriting the mentors.debian.net code once again. The new project was called "debexpo" because it was supposed to become an exposition for Debian packages. It was supposed to be so generic that it could work for mentors.debian.net but at the same time work for personal package repositories or even specialized projects that elsewhere used PPAs (personal package archives). Several applicants contacted me and in the end Jonny Lamb became the student working on debexpo.
The project got very far but then suffered the fate of many open-source projects. The project was 95% done but not well-enough tested and documented that it became useful for others. So the project rested for a while until it was again picked up by a team of enthusiasts around Asheesh Laroia in 2011. They worked hard and finally managed to get my rusty old instance of mentors.debian.net replaced with the shiny new code. The relaunch happened in August 2011 so that after nearly a decade I could hand over the duty. What a relief. :)