Is there a server (ftp server?) that keeps old sage binaries?
I can find any old sage binaries on the web. The sage server and mirrors erase any links to the old ones. I am sure there are kept somewhere.
I would like to try the sage cell server (I need Sage 5.0 on Ubuntu 10.04) but I do not intend to compile the source.
Is there any particular reason you need Sage 5.0 as opposed to a newer version? The cell server works fine (and is developed on) newer ones... Also, compiling from source really shouldn't be very difficult.
The README on the sagecell github pages refers to 5.0 and must be fairly old. I found this list of requirements which is supposed to work for 5.2 https://github.com/sagemath/sagecell/issues/344. I wonder if this is the most recent update?
http://aleph.sagemath.org/?q=1ebcd240-09a2-4ea6-a867-0d00d0e9dc36 indicates that 5.2 works fine with the most recent Sage cell. You may also want to email the developers just to let them know the documentation you found refers to 5.0.