We have set up a Ubuntu workstation with accounts for all the group members.
Nxserver from nomachine seems to be what we need, but it is restricted to two users. FreeNx isn't easily installable and doesn't seem very reliable. VNC seems to be usable for log in to an existing open session, but not for remote logins on a single workstation.
To be clear, we need a solution to log in on a workstation. Desktop maintenance isn't necessary at all.
remmina
Remmina is a remote desktop client written in GTK+, aiming to be useful for system administrators and travellers, who need to work with lots of remote computers in front of either large monitors or tiny netbooks. Remmina supports multiple network protocols in an integrated and consistant user interface. Currently RDP, VNC, NX, XDMCP and SSH are supported.
Remmina is released in separated source packages:
Remmina is free and open-source software, released under GNU GPL license.
screenshots : here
In the old days you started xdm on the machine, and it provided remote X logins to X servers started with "-broadcast" or "-remote" (if I recall correctly).
I believe I have seen that Ubuntu can enable this X display manager, so I would recommend you have a look at if it is still possible.
Cendio Thinlinc can be used with 10 concurrent users in production systems for free http://www.cendio.com/products/thinlinc/. I haven't administered it, but I like the client.
You can try NeatNx. It's a NX Server developed by Google for internal use. You can install it using the FreeNX PPA and afterwards installing neatnx-server.
I haven't used it, but I do use FreeNX in production and it works great. I agree that installation and configuration is a pain. We were NoMachine customers a couple of years ago (their offers were way more affordable then) and they are a really nice company (well at least they were), support from them is great and while their products don't work better or worse than others, they are way easier to install and configure than FreeNx.