WP Permissions (CHMod)

I just realized that my WP themes directory is browsable by anyone - You can go to mydomain.com/wp-content/themes/ and just browse through the directories. Is this a potential security issue? What are the best directory permissions to set for a WP installation? I'd still like to be able to edit files via the WP control panel, instead of via ftp - What do you guys think?

If you use your own theme you don't want someone to use its a problem but if not theres no problem

add a blank index page to it [and any other directory that is 'readily' available]

Beyond people viewing the files though, this isn't an issue?

By default on some Web Hosts directory indexing is enabled to the public_html directory. The fastest easiest way and never have to look back method is by turning off Directory Indexing in your public_html all folders will inherit the default system setting (awesome), if you are using in CPanel go to Advanced then "Index Manager", if you have an application that requires directory indexing then you can as well modify just that folder.