Note that many servers' default installation of GNU Aspell is outdated, so if you update the spellerpages/server-scripts/spellchecker.php ( or .cfm/ .pl) to use the defaults as entered by FredCK, your spellchecker will likely fail. cPanel-based servers in particular will only have v 0.33, which does not have the HTML filter available, nor the encoding option. If your server is using cPanel for hosting, you will need to upgrade Aspell manually, from the command line. If you're on a shared host, you will need to request that your host company do this. You can refer them to the post by "silver surfer" at this forum thread: http://forums.cpanel.net/showthread.php?t=35534&highlight=aspell+rpm

If you have root access to your server, you can update it yourself. Here are the instructions (adapted from the aforementioned forum post):

1. Find out which aspell pkgs are installed, if any.
   rpm -qa | grep aspell
2. If there are some installed, the above will give a list like
   aspell-0.33.7.1-25.3 aspell-devel-0.33.7.1-25.3
3. If nothing listed, go to #4. Else, uninstall those that are listed.
   rpm -e aspell-0.33.7.1-25.3
   aspell-devel-0.33.7.1-25.3
4. Download the updated version and the dictionary files
   cd /usr/local/src
   'wget' ftp://ftp.gnu.org/gnu/aspell/aspell-0.60.5.tar.gz
5. 'w'get' ftp://ftp.gnu.org/gnu/aspell/dict/en/aspell6-en-6.0-0.tar.bz2
6. Unzip the files
   tar -zvxf aspell-0.60.5.tar.gz
   tar -jxvf aspell6-en-6.0-0.tar.bz2
7. Configuring and compiling. The first make will take a while!::cd aspell-0.60.5 ./configure make make install
   cd ../aspell6-en-6.0-0 ./configure make make install
8. Kill any rogue processes, if any.
   killall aspell
9. Add a sym link.
   ln -s /usr/local/bin/aspell /usr/bin/aspell
10. Test it:
    echo "this word is mispeled" | /usr/local/bin/aspell -a -d american -H

Should give you output like this:

@(#) International Ispell Version 3.1.20 (but really Aspell 0.60.5)
*
& mispeled 16 21: misspelled, misapplied, misled, dispelled, misfiled, misruled, mislead, spelled, 
spieled, misplaced, mispla yed, misspell, misfield, misspend, simpled, misplay