You may wash your hands with hot water for any ritual purpose except for mayim achronim.

You must wash your hands (the One-Time Method) if you scratch your head on a place where you have hair. You do not need to wash your hands if you:

• Touch your hair
• Scratch a bald spot.
• Rub your head instead of scratching it.

You may not wash or hang up wet laundry on Shabbat (or Jewish festivals).  The halachot for drying laundry depend on whether you use a clothesline or a dryer:

Shabbat: Laundry: Clothesline
You may take down laundry on Shabbat only if it was dry before sunset on Friday, and only if you don't:

• Transfer the laundry from one halachic domain to another (hotza'a), or
• Give the impression that the laundry had been washed on Shabbat (mar'it ayin).

If laundry on a clothesline is still wet at sunset on Friday, the laundry is muktza and you may not take it down or use it during Shabbat. This is different from the case of a dryer.
Reason On the clothesline, there is no certainty that the laundry will dry during Shabbat (it might rain, it might be cold or cloudy...), so the person cannot have in mind that it will dry during Shabbat.

Shabbat: Laundry: Dryer
Laundry in a dryer (even if it was wet at sunset) that was turned on before sunset on Friday (or Jewish festivals) is not muktza, even if you do not intend to wear it.  You may remove the dry laundry from the dryer on Shabbat as long as no light goes on.

You must wash your hands after touching an animal, before saying blessings or prayers.
 

You may wash and drain olives and other canned fruits and vegetables on Jewish festivals (it is not boreir unless the food in the can is dirty).

To wash hands from tum'a or all other purposes, you do not need to dry your hands first--except before washing for bread, and then ONLY if the person who washed hands before you:

• Did not use a revi'it of water (per hand) to wash his/her hands, AND
• Only poured once on each hand.

In sum, you almost never need to dry your hands before washing them!

However, if the person before you had tum'a on his or her hands and poured only once, the tum'a will be transferred from his/her hands to the cup. 

Wash your hands (without saying the handwashing blessing) before eating wet food, such as a piece of fruit with water on it or simply dry off the food, if possible.

You should wash most fresh fruit cut with a non-kosher knife in order to remove whatever non-kosher food might have been on the knife from before.

You may not wash or hang up wet laundry on Jewish festivals (or Shabbat).  The halachot for drying laundry depend on whether you use a clothesline or a dryer:
Jewish Festivals: Laundry: Clothesline
You may only take down laundry on Jewish festivals if it was dry before sunset at the start of the festival, and only if you don't:

• Transfer the laundry from one halachic domain to another (hotza'a), or
• Give the impression that the laundry had been washed on the Jewish festival (mar'it ayin).

If laundry on a clothesline is still wet at sunset before the festival, the laundry is muktza and you may not take it down or use it during the festival. This is different from the case of a dryer.
Reason On the clothes line, there is no certainty that the laundry will dry during the festival (it might rain, it might be cold or cloudy...), so the person may not have in mind that it will dry during the festival.
Jewish Festivals: Laundry: Dryer
Laundry in a dryer (even if it was wet at sunset) that was turned on before sunset beginning the Jewish festival (or Shabbat) is not muktza, even if you do not intend to wear it.  You may remove the dry laundry from the dryer on the Jewish festival as long as no light goes on.

There is no need to wash a clean wine glass before using it for kiddush.

 

After leaving the cemetery, wash hands using the Three-Times Method without a blessing; see How To Wash Hands Using the Three-Times Method. You can take a container of water with you in your car.

You may wash your hands for any halachic purpose using a squeeze bottle.
 

There is no need to wash a wine glass before using it if it is already clean.  

You should wash your hands, even if they are not dirty, before saying any prayer service that contains the amida, but you do not need to go out of your way to wash them.