Well it depends really, I have seen only a few applications that I can think of at the moment. All of which derive from the WTF patterns. Apart from the ones I've seen, I can imagine that most of the blocks could signify grappling movements to position an opponent. Any knife hand block can clearly be changed into a grab, I will not cover this possibility because it is quite obvious.
It should be noted that these are only my personal analyses, I do not know of any official applications to these techniques. It is also quite difficult to describe these over the net, I will do my best. By the way, I do not think the chamber in TKD is used for much more than increasing strike power and protecting the limb against being grabbed. A large number of blocks in WTF patterns do not use a chambered hand, as you will soon discover.
The first that comes to mind is in Taegeuk Sah Jang, I interpret the initial movement as a downward block to a middle section strike (aimed at the solar plexus) grabbing the striking arm. The striking arm is then pulled down to expose the armpit to a vertical knifehand strike.http://www.worldjidokwan.com/Forms/TaegeukSahJangFormfour.htm
See step 1 and 2 in the website.
I recently found a new application in the same pattern by watching my Jujutsu Sensei perform a throw. The technique is a knife hand upper block to a downward hand strike followed by a knifehand to the throat using the other hand. This strike was used as the beginning of a stranglehold takedown. (Although this may not have been the original intention of the movement because a front kick follows it)
See step 5 in the above website.
In Taegeuk Oh Jang, there is an outward knifehand block followed by an elbow, this is clearly a wrist pull followed by an elbow to the jaw.http://www.worldjidokwan.com/Forms/TaegeukOhJangFormfive.htm
See step 10 and 11 in the above website.
A similar technique can be used by pulling an arm down from a downward strike and elbowing the unprotected face. (i.e. the arm is pulled down to chest leve after the strike hits the upper block and your elbow strikes above your opponents trapped arm).
See steps 15 and 16 in the above website.
I'm not too sure about this one, so please pitch in if you have a better clue. In Taegeuk Chil Jang, there is a technique which looks to me like a grab to counter a punch to the solar plexus followed by a palm strike to the bicep of the punching arm (limb destruction?). Then a backfist to the nose.http://www.worldjidokwan.com/Forms/TaegeukChilJangFormseven.htm
See step 7 and 8 on the above website.
In the same pattern, there is a collar grab similar to a Muay Thai clinch, followed by a knee to the solar plexus. (Proof that knee strikes are used in TKD). This is followed by a takedown involving pulling and twisting your opponent by their dobok collar.
See steps 14 to 16 in the above website.
In Taegeuk Pal Jang, there is a peculiar technique which involves a horizontal arm held infront of your chest and an uppercut afterwards. I am at odds with my instructor as to what this move means. He believes it is a deceptive move, that the horizontal arm is used to hide the coming strike from the opponent. I personally believe that the horizontal arm is grabbing a punch to the solar plexus and then the other arm is used to strike the tricep (again limb destruction) or chin of the opponent (who should be pulled off balance and bending over).http://www.worldjidokwan.com/Forms/TaegeukPalJangFormeight.htm
See step 9 in the above website.
In the same pattern is one of my favourite applications. I interpret it as a simultaneous collar grab and elbow to the temple, followed by a backfist using the same hand to the nose (which should be facing away from the initial strike) and finally a high section punch to the exposed larynx.
See steps 19 and 20 of the above website.
The last pattern I am able to comment on is Koryo (1st Dan pattern). This pattern has some of the most interesting applications. It clearly uses knee destruction roundhouse kicks similar to those used in Muay Thai.http://tkdonline.free.fr/General/Poomsee/Koryo.htm
(Apologies for the image quality, I couldn't find anything better)
See step 2-1 in the above website.
The pattern also demonstrates claw strikes to the larynx. (Many people don't believe me when I say that claw strikes ARE used in TKD).
See step 8-2 in the above website.
There is also what I interpret as a grab to intercept a strike to the solar plexus and a rising palm strike to the undefended chin.
See step 18-3 in the above website.
I think I've chronicled all the applications to techniques in WTF TKD patterns I can think of. Hope this answers your questions, even if it is only my limited experience which forms the foundation of these interpretations.
I will post if I discover any more interpretations later.
I'll say again that these are NOT official interpretations, only my personal opinion. I don't want to start any arguments over this.