The Altitude Map Archive is available at:
The interface allows you to filter the maps by either name name or their type.
Thanks to the enourmous help of @xalri nearly all the maps have screenshots. After getting through only the 1-life maps, I thought my hand was going to fall off. So, I enlisted his help. He build the awsome map_renderer program which works on almost every map. It is currently missing spawn points, but once that is done I will redo the map screenshots.
I have also enabled the map archive for uploads. Use the "+" link in the top right corner to open the upload interface. Uploading screenshots is optional, and if you don't, I will eventually run @xalri's program to create one for it. If you have a screenshot, please upload it. I am trying to automate that, but getting it to run on a stock CentOS 7 based google VM is proving rather difficult. So, please upload any maps you have which are missing.
To map makers: You don't need to use tinyupload or any of those, if you upload your maps here, you can direct link to the map and the screenshot in your posts. That will help keep the archive up-to-date, and provide you with free, persistent storage for your maps.