Now, to be honest, this might have a bit to do with the fact that many people assumed it was the same as Classic TA and did little more then skim the docs, or just jumped in without bothering to find out more then how to build and and attack.
These are a few I've picked out from the changelog and experience and I hope people will come up with a few more, we can organize them into categories and such... I think it's even okay to include things in the ReadMe aswell in the final cut too so people don't have to read two sets of docs... and we can put them on the wiki. There's nothing better then answering n00bs questions by pointing them at the docs

dot commands (entered by pressing enter to bring up the "say:" command line):
.take - Recovers the units of a disconnected ally to your team
.cheats - Activates a number of otherwise inaccessable dot commands
.team X - Changes your team to team number X
.spectator - Changes you to the position of a spectator
Drag Commands:
Some commands, if you click and hold when the command is given, extend the area of effect of that command.
Reclaim+Drag Circle=reclaim all features in the circle
Resurect+Drag Circle=Resurect and Heal all valid corpses in the circle, if used on a group of rez-capable units, group will move on to resurect another corpse leaving one to Heal the first target
AreaAttack+Drag Circle=randomly bombard the area withing the circle
Move+Drag Line=give move command to group to line up behind the drawn line
Load+Drag Circle=Load all units in an area and that move into an area(I believe)
Unload+Drag Circle=Unload all units into area instead of on top of eachother(I believe)
Function Commands:
F2 = Calculate Paths, shows a grid representing where the selected units can move to, when trying to build a building it shows a grid of spots where it can be built.
Features:
In the latest release of spring, features(like rocks and wreckage) are placeable on maps... there is no official version of MapConv that does this but mother came up with this http://www.fileuniverse.com/?p=showitem&ID=1421 which is meant to place them... check this forum topic: http://taspring.clan-sy.com/phpbb/viewt ... sc&start=0
Selection Edititor (in the spring folder) let's you configure special keys for selecting/deselecting/filtering selections, (will include, when done, some examples and directions for creating them)
Additions=RED
Not Sure=BLUE