I don't think most of the songs listed in this thread were B-sides.
By the early 1970s, double-sided hits had become rare. Album sales had increased, and B-sides had become the side of the record where non-album, non-radio-friendly, instrumental versions or simply inferior recordings were placed. In order to further ensure that radio stations played the side that the record companies had chosen, it was common for the promotional copies (DJ version) of a single to have the "plug side" on both sides of the disc.
With the advent of cassette and compact disc singles in the late 1980s, the A-side/B-side differentiation became much less meaningful. At first, cassette singles would often have one song on each side of the cassette, matching the arrangement of vinyl records, but eventually, cassette maxi-singles, containing more than two songs, became more popular. With the decline of cassette singles in the 1990s, the A-side/B-side dichotomy became virtually extinct, as the remaining dominant medium, the compact disc, lacked an equivalent physical distinction. However, the term "B-side" is still used to refer to the "bonus" tracks or "coupling" tracks on a CD single.
With the advent of downloading music via the Internet, sales of CD singles and other physical media have declined, and the term "B-side" is now less commonly used. Songs that were not part of an artist's collection of albums are made available through the same downloadable catalogs as tracks from their albums, and are usually referred to as "unreleased", "bonus", "non-album", "rare", "outtakes" or "exclusive" tracks, the latter in the case of a song being available solely from a certain provider of music.
In the sense that all the songs above are non-album and/or bonus tracks, they're referred to as "B-Sides", which has become a blanket term for these kinds of songs.
Granted, though, some of these songs DO appear on Dream Theater singles, like "Eve", "To Live Forever", and "The Way It Used To Be", while others like "Speak To Me" appeared on a 6" MINI CD on a Japanese release of FII.
-Marc.