In a comment to my post yesterday about A Nice Emacs Dired Command Sue Nymme notes that in addition to 【* t】 a plain 【t】 will also toggle the marks in a Dired buffer. That brings up another Dired trick that I learned from the Emacs Wiki.
You can display only the marked files by using the command 【t k】. This works by first toggling the marks so that the previously marked files are not marked and all the others are. Then the 【k】 kills (that is, hides) all the marked files. You can restore things with the 【g】 command or with the 【t g】 command if you want the files to still be marked. The 【t g】 command is useful if you have a lot of files in the directory and want to see which files are marked before you perform some operation, such as delete, on them.