Backpages.com is similar to Craigslist.com. The advantage here is this totally free. You can any ad you like without any barrier.
The Craigslist.com as mentioned earlier is not for free always. But for some situations it can be used for free. In posting jobs this is a good place. But there is a section named gigs where you will be able to post positions which are temporary for free of charge.
Kijiji.com known as ebay classified ads is one of the free local classified sites. This very convenient, easy way to find people in your city to sell, buy or trade by helping each other. And it is possible to find your next job here. The options they are providing are endless.
Youtube is also regarded as an excellent site with a good community which will provide its users in posting movie files on servers of them in order to be viewed by every person.
Another online service available for free is Google Drive. This is given to its users by Google. Here, you will be able to get a storage space of 5 GB to share your files.
You can also use SmartRecruiter.com which is a unique website. When you establish a company account, you will be able to post ads here and it gets filtered to some other free sites. If you want to get paid and maximize your amount this will be a great option.
E-mail is a location where you can post your ads for free. If you are a person who needs to share files with friends and family and not with all people on Internet, this is a good option. The free email services will give a more storing space to the users. As an example, the Gmail of Google which is more familiar to you is capable in giving 25GB storage space. When sharing photos or videos which are greater than 2 MB, if the other party which you are sending the mail do not have the same service, you will not be able to send your photos or files.
Blogging is also a good way to post your ad for free. Some websites are there which allow you to start blogs for free. It is not restricted to post your ad as a blog entry. The fee blogging sites are Wordpress, blogger, Tublr etc.