Jun, It is all about being polite. Since English has neither polite verb forms, nor a polite pronoun, we have invented many many forms and expression of politeness. Any help is appreciated = the present tense form of your sentence. This 'passive' impersonal present tense form is already polite. It is more polite, for example, than the form "I appreciate any help."--which is also polite. Any help will/would be appreciated.....Your sentence. Will/Would have the same meaning. The use of "will" makes the sentence more polite, and "would" makes it still more polite. The sentence can be expressed as a condition of the form: If you help me in any way, it will/would be appreciated= Any help will/would be appreciated. Or as a polite request. Will/Would you help me? I will/would appreciate any help.

Thanks a lot for your answers!

well , i think both will and would are correct , would 1.用于表愿望、请求或建议的陈述之后。(uesed to express willing ,request or a sentence of proposal) example: I wish you would stay, 2.用于有礼貌的请求。(for a polite request ) example: would like to come to china ? 3.表示不确定之意。( express uncertain ) example: it would seem to be getting warmer. will 1. when uesed as a Auxiliary,it means things will happen in the future . example: he will come back soon.