The title "jam band" is given to popular music acts that lean on extended improvisations over their musical library, which is large enough that no two night-to-night setlists are the same. Outside of the core improvisation fundamentals (see: discussion about Type I vs Type II jams), these bands often transcend the boundaries of any one genre. This has led many to define "jam band" based on the culture surrounding seeing the bands on tour.
While the inherent appeal of jam bands is that ANY song can serve as a launch pad for an extended jam, the songs that most often play the role of tentpole jam contain a certain quantity and/or quality of grooves. When listening to traditional classic/alternative rock radio stations, I often stop to think to myself: "can this song's progression form the backbone of a lengthy jam?"
Evidently, a lot of rock 'n' roll acts ask the same questions; any given live show will generally have hit songs/memorable solos improvised so that they play out longer than their studio cuts. This alone does not make a jam band, as improvising in this regard does not explore uncharted grounds and is not central to the band's (setlist) construction. Ink has been spilled over when the jam band label does/does not apply, and as such songs from the bands listed in the main article page aren't included in this list of songs written by non-jam bands.
Before we get into the titular Top 25 ranking, here's an unordered Top 5 jam vehicles period (all from jam bands) that should serve as a sampler for the type of vibe I'm trying to cultivate from the songs I like to highlight for this purpose, complete with live recording examples:
Listened to all of that? Good. The core Top 25 list is below. Linking to studio cuts of all of these will get repetitive/redundant fast, so sit back and envision these tunes being jammed into yonder.
Finally, some songs that I felt were too damn vast for the main list by virtue of being compositions that take up more than a full side of an LP.