Why angled/tilted tail rotors?
 

Some bigger helicopters have this feature and I can't get my head around it. Why is it there?

It creates a little bit of vertical lift. (I can't remember exactly how much but I think it's in the range of 3-8% of total).

This effectively helps to 'pull the tail up' and hence widen the CofG envelope.


HTH

tilted tail rotors
 

makes them easier to check on the preflight

MD did a similar thing with the 2 smaller NOTAR's, 520 rotates between left and right with the hole in the trash/garbage/rubbish bin going over the top and 600 under the bottom. (From memory) Stand to be corrected on which is which but they differ.

Brave is correct. I think it is 2.5% on the H60 but it has been years....

It was a timid attempt at moving toward the advantages of twin main rotors. ;)

Canted T/R's
 

If I recall correctly Sikorsky did it first on the S-60 which, in its pre-production variant, had a very aft C of G - so it was introduced to overcome the handling issue. Again, from memory I think it provides about 4% of the total lift on the latest and (allegedly) greatest, S-92.

Just adding the arithmetic for Nick.
 

The Blackhawk is canted 20º. The vertical component (lift) is equal Tv = T x Cos20º = T x 0.34 while the horizontal component (anti torque) is equal to Th = T x Sin20º = T x. 0.94.