Whoa. Hell yes, thanks. These will make online more interesting. I just wish I knew them when I was unlocking the staff ghosts. It would've saved me a couple minutes.

Too bad most of them require a mushroom to be accomplished. They separate the noobs from the pros though.

All those are pretty standard... although I haven't managed to pull off the mushroom gorge one yet... but then there is a much better one for mushroom gorge so there is little point.

@Rubang, can I add you in MKWii? this is my code for Americans: 3652-1180-9557

I didn't know about that Mushroom Gorge one. Interesting.

Here are the shortcuts I use when I can.

Luigi's Circuit - cut across last corner with a mushroom (takes some getting used to to miss the pipes).
Moo Moo Meadows - boost across the sweeping left which the second set of cows are on.
Mushroom Gorge - In a race boost around the last corner on the grass, in a time trial I boost across the gap for that last corner, it is incredibly difficult to pull off though.
Toad's Turnpike - None really, there is one on the last corner (use the little hills to boost over the water) but I have only pulled it off once.

Mario's Circuit - cut across the grass after going though the tunnel, or in a race (not TT) across the grass/gravel where the chain chomp is.
Coconut mall - cut through the shops at the first corner.
Snowboard Cross - too many to mention... the best one though is on the last corner, if you go off the right hand edge of the half pipe just before the corner your jump in mid air will turn the corner for you and you land facing the final straight.
Wario's Gold Mine - obvious one by following the mine carts.

Daisy Circuit - boost up the stairs through the building that is just before the "8" shaped bit.
Koopa Cape - 3 nice ones, across the grass where the goombas are, or cut either or both of the two main corners in the river section.
Maple Treeway - same as the video, in a time trial you need to boost across the offroad bit.
Grumble Volcano - A number of little ones (boosting at the right time to miss the sliding platforms, or cutting corners) but the main one is to boost onto a little island which is in the middle of the bit you go round with the falling rocks/fire, quite difficult to bounce off it and onto the track at the other side.

Dry Dry Ruins - the one in the video, or across the last corner, or boosting through the indoor bit (just after the first bats) or if you go up the half pipe bit correctly, you can do the same thing here as on Snowboard Cross.
Moonview Highway - None really specific just get a good line and work out a goos route with the boost strips, (don't use the high up one unless you are no good at driving through the traffic)
Bowsers Castle - use the left half pipe bit for both of the mud sections (go up the first one shallo so you land early, and turn left when you land to use the next one in the same way) or boost across the mud, although this is actually no faster than using the half pipes and wastes a boost.
Rainbow Road - time the boost right and you can jump clean over the left hander after the "8" section, check out the world time trial leader to see it (or youtube), it's actually quite easy to pull off once you get used to it, so you can use it in a race too.

The shortcuts just seemed too obvious now that I know.

The one in Delfino Square I already knew from DS. Also, there is a narrow opening on the right with mud if you didnt take the other shortcut. Using a mushroom will make you go faster but if you dont watch, you could go falling into the water!

The one in Rainbow Road is hard but looks cool.

I knew the one in Delfino square, the rest looks interesting....

thats why I never win...