I would like to install program foo using emerge on a Gentoo system; so I simply use emerge foo to install and portage selects the most current version of that software that's in its repository. If I know the version number and the naming covnention, I can do emerge =foo.1.2 and use eselect to chose what the currently inforce package is out of the installed ones, if the package supports it. But what if I don't know the version number or naming convention and just want a list of what's versions of foo are available to me? I don't see an emerge option that does this and snooping around under /usr/portage doesn't yield me anything.Bonus: Is there anyway to find what locations emerge polls to determine what packages are available? For example, many of the ebuilds on my systems are in nonstandard locations, but emerge finds them anyway, so I'm attempting to determine how emerge builds it's list of available software versions.   
Portage on Gentoo how to view available software versions?
gentoo;emerge
While I would recommend lkraav's solution, here is another way:$ ls /usr/portage/app-portage/eix/ChangeLog  eix-0.25.5.ebuild  eix-0.29.6.ebuild  eix-0.30.1.ebuildManifest   eix-0.29.3.ebuild  eix-0.30.0.ebuild  metadata.xmlthis will of course only give you list of all ebuilds available for eix in the portage tree (without all the nice info which eix does provide).If you are using layman more ebuilds will be available in overlays (basically in other folders).