I had also been annoyed by this but just today I seem to have found a way that works for me.
I had tried setting up a catalog in Aldiko but could never connect. I had the same problem many here have posted about - it kept prompting me for my username and password over and over.
I tried setting up the url as
http://calibre_server_ip:8080 as well as tried the suggestions of adding /stanza and /odps at the end with no luck.
I have finally gotten it to work by using the basic url
http://calibre_server_ip:8080 but I changed my calibre server settings so there isn't a username and password.
It now connects like a charm. I have been able to grab books in Aldiko just as easily as I could in Stanza on my iPhone - and with just one copy on the Droid.
Not having a username/PW isn't ideal but in the meantime it works.