QUOTE(Why @ Sep 27 2007, 08:31 PM)

Is it authorized to put text in an image and make a link on it?
Of course. It's used by many, many sites for their site navigation without any problems. Naturally, without alt attribute text these graphical links won't be particularly accessible to the handicapped.
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With javascript, the anchor text will be not seen by google? sure?
If the Javascript is used to write out the link, yes, we are sure. Again, those links won't be accessible to the handicapped, either. To test it, bring up your page in a text-based browser (maybe use the Yellowpipe Lynx Viewer Tool plugin in FireFox, or just install Lynx itself) or in a regular browser with JS turned off. If you don't see that text at all or you see it but not as links, then the SEs won't see them as links either.
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Trying to hide them is liable to bring down many more problems than simply leaving them, especially when your reason is something as pointless as word density.
To be honest, I agree...
--Torka