Ultimately there has to be some "sequencing of events" in an adventure, assuming the NPCs aren't static. If the NPCs were static, I think that would be a site based adventure.
L2 - Assassin's Knot (DnD 1E, TSR)
There is some information of when individuals will take certain actions. However, how the characters find the assassins, what they do about it - is all up to them. There is no "linear" part of the adventure really.
W1 - Conquest of the Bloodsworn Vale (DnD 3.5E, Paizo)
There is a calendar of events, but player decisions as to when and how to handle events impact their success greatly (they need to oversee the building of a road that is having many challenges). Even details of deciding to scout or not scout can have impacts (especially at different times in the plot, if the players are away for a major event).
W1 - Wizard's Challenge (DnD 2E, TSR)
There is a basic sequence of attacks, but the players actions can radically change the outcome (if you overlook a few heavy handed lines that say something like "just have this happen anyway, like when the PC goes to the bathroom"). Minimal adaption.
WOTBS (War of the Burning Sky) #3 - Shelter from the Storm (Dnd 3.5E ENWorld)
The main plot can be done linear. However, with the large number of side quests that obviously have impact and the hard schedule (so that doing all would be very difficult), player actions and choices (to do one thing but not another) have consequences.
N1 - Against the Cult of the Reptile God (DnD 1E, TSR)
While the cult lair is a dungeon dive - the town provides a fertile setting for non-linear nature (which events happen when are largely up to the DM and player reactions). The adventure doesn't describe how to support this style of play; the adventure seems to just assume the DM knows how to do non-linear play in the town setting.
That's what I can think of off the top of my head. Most of my books are in storage as I move cross-country. If you need more than that, PM me and I'll be able to look into this more in a week or two.
