Is there any ready table to convert units and values? A sort of universal table for all kinds of units and values including currencies.

I'm not sure if you are wanting just a list of conversion factors(for use with a calculator) or a table that will allow conversions without doing the mathematics. For a comprehensive set of conversions the later would fill a small book.

For measurement functions it's convenient to use your web browser. Bookmarklets/Favelets make this easy see the links at:
Bookmarklets - Calculator and Converter tools (http://www.bookmarklets.com/tools/convert/index.phtml)

Most of these allow you to enter a value in a pop-up and display the converted measurement afterwords. There are bookmarklets/favelets for other purposes, some of which require you to select between versions depending upon which web browser you are using.

Currency is more of a problem, because the relative value between two currencies is usually fluctuating

I have a chart that I have been assembling for a number of years. Let me know if you would like a copy and I will e-mail one to you.