URL Format - with our without trailing slash

This may be an odd question, but it's something that's come up more than once.

Does anyone know if it makes a difference if a link has a trailing slash or not? For instance, which of the two links below should I use for links to my site:
1. http://www.domain.com
2. http://www.domain.com/

The reason I ask is twofold. First, if you use the Google Toolbar and click backwards links on my domain, it appears as the following: "link:http://www.domain.com/". Perhaps Google values a URL more highly with a trailing slash?

The second reason is that if I (again using Google toolbar) check to see the cache on a certain page, there is a difference between the same URL, with and without a trailing slash. For instance
- http://www.domain.com/Directory/SubDirectory/ (No cache)
- http://www.1aauto.com/Directory/SubDirectry (Cache)

There is zero difference between these two URLs and their content other than the trailing slash. I find it odd that Google differentiates between the two at all?

Any thoughts/ideas?

I don't know why, but I've always used the trailing slash.Just habit I guess, but I have read others say its the way to go.