I have noticed quite a few different companies putting a login script on the front page for their customers. Has this been proven to be effective? Just looking for the PROs and CONs on this.

We used to do this actually, and thought nothing of it. We used it just to fill space.

The day we launched a new design, and removed the login box, you'd be surprised at how many people wrote asking for it back.

It is a convenience for them, that is the only Pro that matters.

Well I think it makes things a lot more secure for customers and makes things a lot easier to manage from their point of view. I think it's better to have on your front page.

It all depends on your site. If you are managing a business site then you should do that to keep your content secure. If you are having nice content based site then it is not advisable to have one on the index page itself, rather they(users) would go somewhere and find the needed information, without registering. Actually people hate to see the login screen everytime, and they tend to move to other sites.

From my prospective a link is fine. You don't need the entire selection. My solution was to create a link which effectively drops down a small box which allows you to enter a Username & Password and a Login Button.

It is easier for some clients to remember the url to access their account.

I think clients would benefit from it, however we don't do it on our site because it would be to messy. Some other designs are suitable for logins though