Just in case you decide to drop a folder or an application into this folder, it would be better to have chmod run recursively:

do shell script "chmod -R +rX " & fileName

The capital 'X' tells chmod to only add the execute bit to things that it is appropriate for (such as subfolders) and not to data files. It comes in really handy if you are trying to recursively add, say, group permissions to a subdirectory. If chmod -R g+rX sees that a file already has owner execute, it will add both group read and group execute. Otherwise, it will only add group read.

I like this tip! I'm going to set it up for ~/bin.
Also, both Smultron & Textmate have menu items to make the current document executable.

Correct me if I'm wrong, but I don't think this is right:
do shell script "chmod -R +rX " & fileName
The point of the hint being, to make files executable that aren't already.

Also, I would do it more like this:
chmod -R u+x
I don't want a whole folder of files that are executable by anybody & everybody.