asking to help someone

Hello there,
Can anyone give an advice on how to ask someone if I could lend them a helping hand. For ex, if I visit my friends parents house and wanted to help them do the dish, laundry, or other house hold chores, how do I ask them in Japanese? (If they don't understand English at all. ^^ )
I don't like being one of those guest who sits back and while everyone is doing something :)

If you see someone doing those things, and you want to ask, you can say:

すみません、てつだってもいいですか。
sumimasen, tetsudattemoiidesuka.
Excuse me, may I help you?

Simply...
わたしもやります
watashimo yarimasu
Also I'll do it.
やらせてください (if they declined you)
yarasete kudasai
Let me do it.

short one.

tetudai mashou ka ?
てつだいましょうか？

Thank you so much for the answer everyone :)

If you already have something specific in mind to help, the phrases given would be useful. But probably the most common phrase we use is;

Nani ka o-tetsudai shimashou ka?
(Shall I help you with anything?)

This phrase can be used in any situation, even if the other party isn't doing anything.

Thank you :)
How about, something more specific like , "please, let me help you with ......."
".....を手伝わせてください"
is rhis o.k?

That's perfect.

Examples:

お皿洗いを手伝わせてください。
(Let me help you with the dishes.)

お台所を手伝わせてください。
(Let me help you with the kitchen.)

片付けるのを手伝わせてください。
(Let me help you clean up.)

Thank you so much "uco" ! That' s very helpful because those are some of the things I treid to say last time but failed ^^; Getting ready to go back to Japan tomorrow and will surely use it ^^*