Well, for the most part bisk's ability is one of the actual few abilities which have real world applications. I mean, the sheer amount of things which that could do for us is astounding to say the least. In particular, the ability to reduce resting time to 30 minutes.... How is that not awesome? Gotta cram an entire semester in two days? Sleep with her ability every 4 hours and you are good to go for that A. Have a deadline but not time to sleep? Nonsense, there is no such thing as no time to sleep if you only need 30 minutes for the equivalent of 8 hours of rest. Stressed out and tired? Nonsense. The ability makes you superhuman in a real world scenario basically.
Now, lets take a look at other abilities. Shalnarks and any other's control? Ok, having something which allows you complete control over someone if you fulfill some conditions is useful... if you are a rapist. Basically just about anything which manipulation allows does not have any legal real world applications.
Nen bullets and projectiles are cool without a doubt and they certainly have their uses. Still, not a single one of them would be useful in a real world scenario. Nen bullets and projectiles are basically only useful if you are a cop or in the military. I would question the extent of the usefulness when you have to have the precision to kill of someone 3 miles away with the tip o your finger though.
Reinforcement... Ok, now this is actually useless. Enhance a sword? Get shot in the head, enhance a fist, get shot in the head. What are the practical uses of smashing stuff ultimately? If there was a job which required super strength, would you trust it to a person with it or a machine with milimetrical precision?
What good is hisoka's ability? It does not even work well when separated from her body. Deceiptful texture? Useful if you are a con artist. Electricity? Ok, you can tazer people but we just happen to have tazers for that. Nen string? Ok, that is useful as fuck. Seriously. A nen string would be inherently sterile so from a medical point of view it is beautiful. Still, it loses a bit of use when you lose contact with it... Nen bombs? Useful if you work in a mine I guess.
As far as conjuration.... A vacuum cleaner which sucks stuff infinitely? This is probably the single most useful ability since bisk's. Just aim for the dusk in the room and you got a clean house in 0.0001 seconds. Not bad at all. 10 in one weapons? Not actually useful. Chains of fury? Ok, kurapica's ability to douse is useful. We would never misplace stuff and perhaps kidnappings would be more easily dealt with. A chain to heal? Ok, it works although none of us really gets hurt that often really. Chain of judgement? Ok, I guess imposing a few on criminals could result in a drastic decrease in crime rates. It would be useful if placed on politicians too lol.
Kannon.... would be useful in a power ranger scenario for the most part.