Here is a list of 8 free services for scheduling social media updates:

Free Multi-Platform Services

If you or your company has an extensive online presence across multiple social platforms, these tools would enable you to schedule social media updates across multiple platforms.

Hootsuite

Hootsuite has a broad range of apps, such as their web-based original, mobile apps for iPhone and Android, desktop apps (Windows, Mac and Linux) and add-ons for Firefox and Chrome, all with the power to schedule updates. The desktop and web-based apps allow you to schedule to Twitter, LinkedIn Ping .fm, WordPress , MySpace and Foursquare. However, the mobile apps are limited to Twitter and Facebook.

CoTweet

This service helps in monitoring a brand's Twitter accounts and engaging with customers. One of the many features of this tool is its ability to schedule tweets by time and date. CoTweet can also be configured to send updates to Ping.fm. The Ping.fm configuration enables you to send updates to any of the social platforms that your Ping.fm account is hooked up to.

FutureTweets

This service enables you to sign in using Twitter OAuth. All you have to do is choose your time zone and get to tweeting. FutureTweets also gives you the choice to "flip" your tweet upside down and in reverse.

Twaitter

Twaitter requires you to log-in with your Twitter information, choose your time zone, and provide an e-mail address to schedule your tweets. Scheduled tweets appear in a queue and can be edited or deleted prior to being sent. This service also features a built-in URL shortener, spell checker, and the abilities to translate tweets, save drafts and mark tweets as recurring. You can also connect your Ping.fm account to Twaitter and begin scheduling updates.

Dynamic Tweets

This service allows you to schedule tweets in advance by the hour or for a specific time and date. One of the most unique features of this service is the ability offered by it to upload a CSV file of planned tweets, include information for the time, date, Twitter account, tweet and optional tracking code. This feature is useful for companies that have massive lists of scheduled tweets planned.

Taweet

Taweet enables its users to schedule future tweets in coordination with events they are planning on participating in. This feature gives you the option to share a tweet that announces your future tweet.

TweetSched

This desktop app enables you to schedule your tweets by date and time. The simple interface includes a text box, add button and queue where you can edit and delete pending tweets.

Tweet-U-Later

Tweet-U-Later features three main options: Scheduling a tweet, scheduling a private message, and scheduling tweets via e-mail. When scheduling a tweet, you are required to choose the time, date, time zone, message, and also choose whether you'd like the tweet to be a recurring message. Pending tweets appear in a queue, where you can edit or delete them.

To schedule tweets via e-mail, you are provided with a Tweet-U-Later e-mail address. In order to successfully schedule a tweet via e-mail, you must follow this format: "Your message goes here;YYYY-MM-DD@HH:MM." This option seems extremely susceptible to human error, so be careful if you plan on using it.

Hope that these tools would help you manage and stay connected with your social media communities in a hassle-free manner.