wget -nd -r -l1 --no-parent -A.pdf -A.ps http://www.foo.org/pdf/

-nd   do not create a hierarchy of directories (save all recursively retrieved files in the current directory)
-r      recursive retrieving
-l1    set maximum recursion depth to 1 (stay in that folder): set to 2 if necessary
--no-parent     do not ever ascend to the parent directory
-A    specify file name suffixes or patterns to accept (-R to reject)

Batch download files from a web directory

http, download

Bash