[Tichy]

"Having separate pages at /foo and /foo/ is completely legitimate"

But also very confusing.

[Terretta]

Not at all. One's a document and the other is an index list unless the list is replaced by a default document.

Also, leaving off the slash to an index will usually cause the web server to do a redirect to to corrected URL with a slash, causing your user extra latency and your server extra hits.