Great info on the F1 help feature, thanks !!!

There was another feature that I thought about the other day when I was logged off that I guess isn't really a Sonar feature per se but cab/mic/position options in TH2 have REALLY helped me understand mic placement for guitar cabs in real life better. It's one thing to watch videos or read articles about that kind of thing but without a proper room and a plethora of mics it's really hard to get a grasp of exactly what it all means. Being able to switch through commonly used mics and move them around in a virtual environment to see what happens is REALLY cool. GR5 has some of these options but nowhere near the flexibility of TH2. Man I love that program and I likely never would have tried it if Cake hadn't tossed it in with X2.

Beepster
cab/mic/position options in TH2 have REALLY helped me understand mic placement for guitar cabs in real life better. It's one thing to watch videos or read articles about that kind of thing but without a proper room and a plethora of mics it's really hard to get a grasp of exactly what it all means. Being able to switch through commonly used mics and move them around in a virtual environment to see what happens is REALLY cool. GR5 has some of these options but nowhere near the flexibility of TH2. Man I love that program and I likely never would have tried it if Cake hadn't tossed it in with X2.

Agreed, I wrote an article for Guitar Player about miking cabs and suggested they start with the miking options in amp sims to familiarize themselves with the variables. Sort of like a flight simulator.

I also use the fretboard view (as well as TAB) in the Staff view just to easily recall how I played the guitar part, and use "Regenerate TAB" very often. The fretboard/TAB and the Matrix view I mentioned earlier are both helpful for someone like me who can't read music. These underrated features are part of my reasons why I don't feel like using the other daw I own as often these days.

One feature I am in the habit of using and tend to take for granted is the use of the numeric keypad for "Nudging".  I have 1 & 3 set for moving by one bar (left & right), 4 & 6 for 1 beat and 7 & 9 for ¼ beat.  And of course 8 & 2 are for up and down.  It's great for moving short clips around accurately, whereas when using a mouse there is a risk of misalignment if you are not careful.  Nudging up and down is an easy way of moving a clip from track to another.  And don't forget that nudging also works within PRV for moving individual notes or note selections.  For transposing midi, nudging is the quickest method.

+1 to Nudging. I use it a lot, except in the PRV when there are multiple take lanes because it has a serious issue (often moves the selected note events to another lane in the track, and can also wipe non-selected note events!): 
http://forum.cakewalk.com/Nudging-note-events-in-take-lanes-doesnt-work-properly-Confirmed-by-CW-m3023030.aspx
 
I'm really hoping it will be fixed soon.
 

Haven't read through the entire thread yet, but thought I would share one of my favorite tricks.  This uses MIDI Learn in conjunction with automation.
 
Often I find myself adding automation to my synth tracks but I am not sure which parameter will give me the best bang for buck.  So I draw my curve for a little used Controller and pick a section of the track using the instrument I am using for sound design.  I start the sequence and then pick a control that I want to automate.  I turn on MIDI Learn and Sonar will immediately assign the existing automated controller to the control.  I can then use Unlearn and Learn to listen to the effect the automation curve has on any control available on the interface of the instrument without reassigning the automation data to a different controller.  It's a real time saver.
 
Hope this helps!

Here's another one: If you set up a circuitous path in the Sonitus surround panner and turn Doppler up all the way, you can get some really bizarre, almost "scratching" DJ-type effects out of any audio source. Very twisted.

Tab to transient on a drum track or start of a split drum clip. Paste in a drum sample and drop it down one track, line the phaze up. Instant drum augmentation.

crossfade sustained vocal note with a slow envelope into a synth note, ala Pink Floyd Animals. If you do it right you can't tell where the vocal ends and the synth starts and it's super easy! Then you can totally mangle the note with controller knobs at the end (or just let the preset do it if the patch allows)