Dont use Orkut or any other social networking communities unless you are a very big company and are sure that a group of your onw clinets cannot mob you off your business.
If you start a forum for your hosting company in the initial stages and leave it unmoderated, naturally you will get links of sites of people posted in their footers, you will get intentional bad reviews from competition or people who dont wish to see you grow, and when a group forms, they might just go ahead and start their own business, every one serving one another.
Dont do that.
Maintain a mailing list, and send out newsletters to everyone once in a while, give them offers, create polls, create offers and stuff.
Or, add them all to various instant messengers that are available online such as Yahoo, MSN, ICQ, AOL, Gtalk and Skype. This way, all clients would need to add you first to chat with you, and it is easy for them to follow you up, and for you to follow them up. And if any one finds the other annoying, the “block” option is always there. Never send bulk messages to entire groups in chat messengers. Use a software such as pidgin that can work with multiple messenger ids at the same time, and this would improve the effeciency of your work.
Always use a helpdesk system to provide support, and never let the support techs to be on chat with the clients. Employ seperate staff for support chats, who can communicate with the techs without annoying them and get the result.
Clinets will not be kind when they have got issues on the server. They will always think that they are on the centre of the world and that nothing else matters to them. So, if they speak with that attitude to the support techs, they might get annoyed and their effeciency might reduce. Also, to handle helpdesk mails, it is advisable to have staff who could do that.
Never let your support techs come into direct communication with your clients, since it could mean disaster. Clients are important for you, and so are the support staff. So give importance to both, and have medeiating staff.