I was researching how something was going to work for me this year and came across this:
It's a searchable and hyper-linked on-line edition of the US Internal Revenue Code. Someone's done a lot of work! No, it's not bang-on current (it's to 2004), but it's pretty good for many purposes.
From the web site's description:
"The complete Internal Revenue Code is more than 24 megabytes in length, and contains more than 3.4 million words; printed 60 lines to the page, it would fill more than 7500 letter-size pages. Looking for something buried in that mass of verbiage can be daunting. By harnessing the freeWAIS-sf indexing and retrieval engine to the Web version of the tax code, you can search the entire Code for words or combinations of words, navigating directly to sections that matched the query by following a link. For example, entering "forfeiture AND beer" in the query box and pressing Start search locates all 13 sections of the Code containing those words, ranked in descending order of relevance as determined by the weighting algorithm in freeWAIS-sf. You can compose more complex queries using the standard freeWAIS-sf query syntax."
This site also has a link to the text of the U.S. Immigration and Nationality Act.