I know there is a way to block Xanga users completely, but is there a way to keep just one or two people from reading just one entry?

I don't believe there is, because you would have to use .htaccess to block their IP, and xanga isn't a proper webhost that they would allow that file type.

yeah true .... but heyy ... iph u d0nt want dem to read it.. den dont type it ... -.-

http://help.xanga.com/blocking.htm