I like to make org-mode tables in arbitrary buffers, then save them as CVS
files. The export fails when done from a buffer with no associated file.

 Here's a little patch that allows exporting a table from any buffer
(org-mode version 6.28trans):

diff --git a/lisp/org-table.el b/lisp/org-table.el
index 410f721..4b85f97 100644
--- a/lisp/org-table.el
+++ b/lisp/org-table.el
@@ -471,8 +471,9 @@ property, locally or anywhere up in the hierarchy."
        (error "Abort")))
     (if (file-directory-p file)
        (error "This is a directory path, not a file"))
-    (if (equal (file-truename file)
-              (file-truename (buffer-file-name)))
+    (if (and (buffer-file-name)
+            (equal (file-truename file)
+                   (file-truename (buffer-file-name))))
        (error "Please specify a file name that is different from current"))
     (unless format
       (setq deffmt-readable org-table-export-default-format)