Okay, IANAL, but...
No, you don't need permission from a website author to cite their works any more than you need permission from the author of a book.
In fact the current MLA standards provide formats for including URLs as citations.
This is just one summary based on those standards, that popped up on a Google search:
http://www.westwords.com/guffey/mla.htmlBut I wouldn't worry about date of retrieval if you're just giving pointers.
I.e., if you quote from a website, or use information on it to support a point you're making, then your footnote or bibliography needs to include the date you retrieved the information. I take this as a nod to the ephemeral nature of website publication, where text can change or disappear at a moment's notice.
But if you just want to say, "Look here, this is a good site," then I don't see that as necessary.
Here's a more comprehensive meta-guide to citing electronic sources:
http://www.ifla.org/I/training/citation/citing.htm