I would like to proudly announce that Opal is releasing colored coins, effective immediately.
Colored coins allow you to create an on blockchain asset, which has tons of potential use cases.
The implementation is Open-Assets compliant and we are excited to have you try it out.
GUI is in development, but you can try it out command line with
http://github.com/opalcoin/colorcoreIn the current Opal implementation, outputs represent a quantity of Opal, secured by an output script. With the Open Assets Protocol, outputs can encapsulate a quantity of a user-defined asset on top of that Opal amount.
There are many applications:
A company could issue colored coins representing shares. The shares could then be traded frictionlessly through the Opal infrastructure.
A bank could issue colored coins backed by a cash reserve. People could withdraw and deposit money in colored coins, and trade those, or use them to pay for goods and services. The Blockchain becomes a system allowing to transact not only in Opal, but in any currency.
Locks on cars or houses could be associated with a particular type of colored coins. The door would only open when presented with a wallet containing that specific coin.
Really cool feature !
Tickets
Tickets are transferable bearer tokens which are designed to be eventually redeemed for some kind of real world value.
Examples of tickets include:
Event entry passes
Store coupons and special offers
Frequent flyer miles and other redeemable rewards
Certificates
Certificates are transferable and redeemable in the same manner as tickets, and they additionally entitle the bearer to some kind of revenue paid through the blockchain.
Certificates can be used for bearer securities, such as securitized loans, mortgages, bonds, and dividend-paying stocks.
Smart Property
Smart properties are transferable like tickets and certificates, and in addition, every particular smart property is both unique and atomic. Only one smart property of a given identifier can be created, and once created it may not be subdivided.
Smart properties can be used to indicate ownership of an unique real-world asset, and can also be used for objective naming of content-addressed mutable data. This naming function is related to, and an extension of, hash-based naming.
A common operation in software engineering is to use cryptographic hash functions to create short identifiers for large pieces of data. This is useful because hash values are easy to communicate since they are short, and also are easy to check since they are deterministic. This means if you know the name of some piece of data, you can independently verify that you have the correct copy of it. But the limitation of hash-based naming is that the named data can never change.
Smart property overcomes this limitation. Because of a Bitcoin feature (OP_RETURN) that allows arbitrary data to be attached to transactions, every time smart property is moved it can be associated with a new hash. This means if you use the smart property as the name of your data instead of using the hash, you can change that data and everybody who knows the identifier of the smart property can identify the most current version of the data.
This is an exciting new capability with deep implications, and we do not believe we have fully mapped out all the possibilities it opens up.
-http://monetas.net/monetas-brings-colored-coins-to-btcd/
I'm still holding my OPAL and know that they are worth the holding for sure 
