You will have to lose some of the more important abilities to become one of the dead stuck in limbo I am afraid. It is true that you won't be able to enter the common rooms or own a house (though haunting one is still a possibility) but you will be able to do more than enough things to make up for the loss.

This is taken from the Harry Potter Wikia:

A ghost is the disembodied spirit of a once living wizard or witch. Many ghosts take up residence within Hogwarts Castle. These fleshless spirits were either afraid of death or have some extraordinarily strong connection to the locations they haunt.

In their paranormal state, ghosts are unable to cause much physical influence. They are visible, and appear as a greyish-silver apparition of their former (living) selves. They may not touch or physically move objects, however in passing through an object, they may impart a sensation of icy coldness. Ghosts are either capable of, or pretend to be capable of, almost being able to taste rotten food.

Ghosts also appear to celebrate their deathday, as Nearly Headless Nick did.

They are also weightless and may fly in any direction. In 1992, a fan was used to blow Nearly Headless Nick away. Ghosts cannot be destroyed, however, they may be petrified with the gaze of a Basilisk. This may be reversed by a Mandrake Restorative Draught, though the method of administration is unclear.

The main reason for a ghost character (at least for me) is not let death be the final end. This can be proven useful for site wide plots are taking place.

Of course like all creatures insides HOS, there will be rules that will need to be followed. A developed character for one (random ghosts aren't fun), post count secondly and most importantly at least in my eyes is the death.

The development of a character when they are alive is important for deciding if they should become a ghost inside of HOS. What they do while they are alive and things they have accomplished will judge how committed they are and will prove they won't just poof away.

Post count is important, I don't know whether it should be higher than the other character types or not. I will leave that decision to the mods if they decide to pick up on the idea.

The death of a character should be the key deciding factor (but not the only one) for a mod if the applicant should be able to become a ghost or not. How the character died is important as well. Moaning Myrtle was died by basilisk eye-contact, though that isn't the reason she came back as a ghost. She returned to haunt Olive Hornby whom teased her about her glasses which caused Myrtle to be in the second floor bathroom when Tom Riddle was opening the Chamber of Secrets.

As the wikia states, one must be afraid of death or have a strong connection with a location or strong desire for revenge in Myrtle's case. Its more of a challenge to actually become one (which is a grim realization for me as I am typing this response) but its still an interesting option for Roleplay.

This suggestion has come up before and I really don't remember what the final decision about it was, I could have sworn it got passed before. But then again I have been here for over 5 years, its hard to remember everything. Anyways, I love this idea and I always have. I think it would add some fun to the site and make for some fun plots and threads. Of course if passed I know there would be a sign up and application to be a ghost, but that goes along with most anything. Well anywho, I support.

Okay...I want to start by saying I don't think this is a bad suggestion. I like the idea of RPing with a ghost. I'm perfectly fine letting other people have there characters become "ghost characters" as long as a couple things are done.

Pardon my blunt early morning honesty.

1. A stringent application process with the mostly usual suspects: a higher post count than many of our current powers/abilities/creatures, a very high quality RP sample, and a valid in-character reason for becoming a ghost.

Properly role-playing a ghost isn't going to be an easy task, so solid familiarity with the site and how folks RP on here should be a must. It will also help make sure that there is a good solid background to the character. A somewhat new character may not have the relationships built up around the site to make RPing with their ghost character interesting. It will also go towards a decent death plot.

2. Once a ghost, there is NO returning to normal for ANY reason.

There is nothing in the literature to suggest that even as a remote possibility. It will also ensure that someone is completely serious about being a ghost.

3. There is a cap on the number of active ghosts allowed.

Really should be self-evident on this one.

As a random note, ghosts, if approved, should be allowed to teach certain subjects (should the job become available). There is support for it in Professor Binns, the History of Magic teacher. He is able to turn pages in books and I think write on his chalkboard. ^_^

One more think i might add, though: it has to make sense for that person to become a ghost. Remember in one of the books (five or six?) when Harry was bent set on fining a way to communicate with Sirius? The Gryffindor ghost pointed out that only those not brave enough to go beyond became ghosts. It would have to make sense with the person's personality to become a ghost -- chances are those who are courageous or otherwise would decide to forge ahead.