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I know these two structures are correct, but are any variations also correct?
For example,
1. It's no point ...-ing
2. It's no point in ...-ing
3. There's no point ...-ing
4. There's no point in ...-ing
...or any others...
Comments  
1. It's no point ...-ing
2. It's no point in ...-ing

These 2 are not correct. You could use 'pointless' + ing" - "It is pointless crying for the moon"

3. There's no point ...-ing
4. There's no point in ...-ing

Yes, you can use these -

"there's no point crying for the moon"

"there's no point in crying for the moon"
And what about:
5. There's no use ...-ing
6. There's no use in ...-ing
?
Students: We have free audio pronunciation exercises.
Yes, you can use this the same way.
To summarize, the following variants of "There's no point in" can all take the gerund (-ing form). The ones you've already mentioned are the most common.

It's [pointless / useless / hopeless / futile / a waste of time] ...
It's no [use / good] ...

There's no [point / use / advantage] (in) ...
There's no [profit / benefit / gain] in ...
_____

Sometimes heard:

There's no advantage to ...

CJ
Just one more question: is it equally correct to say:

- It's useless TO LOOK...
- It's no use TO LOOK...
?
Students: Are you brave enough to let our tutors analyse your pronunciation?
demicjusz,

The gerund and infinitive are not always interchangeable.
Only the first line of my examples above can take the infinitive in place of the gerund.

Hence, "It's useless to look ..." is OK; "It's no use to look ..." is not OK.

Jim