The main idea of CraigsCoin is to provide the world with trustless, decentralized classified ads listing. Since everything is stored in the blockchain no entity will be able to delete or somehow edit an ad once it is posted. CraigsCoin is essentially decentralized database of ads that can be implemented on any website or any other third-party technology.
CraigsCoin utilizes a modified blockchain in order to allow any user to post their ADs directly into the blockchain. Normal transactions between users will be no different from any other coin out there. There will be a "special" wallet that will accept special type of transaction, called ADTX (AdvertisingTransaction). In first prototype version of CraigsCoin ADTX's will have fixed cost (i.e. you can only sent 5 CRAIG to ADTX wallet). This cost is called Listing Fee. In the current build of CraigsCoin listing fee has a fixed value of 5 CRAIG, however in future releases ADTX may be recalculated depending on the price in order to indirectly reflect CRAIG market value. Every message to the ADTX wallet will look like genuine transaction with one exception - this transaction may contain user created message (Ad text). This may be any message from 1 to 10 000 bytes. This message will be readable by anyone using custom block explorer. It is as simple as that.
Can somebody tell me, why I would want to put my AD in a blockchain? What is the big advantage?
You need to find answer on this question yourself, otherwise you always will be on marketing and PR hook. Many people not enthusiasts, they use things don't thinking about why or which is better, they just using them and thats all. I don't see any huge outstanding advantages, as I don't see reasons, why this project can't grow with time to crypto eBay level.
This project will need people, many people, otherwise what the point of an ad site which are browsing just a few individuals. Working, looking nice and user friendly product + promotion, truly work wonders.