Here is a response from Poker Stars:
Hello wisak7,
Thank you for contacting PokerStars.
Regarding the question posted in your forum:
W$: What do you do with them?
Let us inform you that W$ can be used to register into any qualifying
special PokerStars event. A special PokerStars event is defined by
PokerStars, and special events currently include:
* Millionaire Quest (World Series of Poker)
* PokerStars Caribbean Adventure (PCA)
* PokerStars World Championship of Online Poker (WCOOP)
* European Poker Tour (EPT)
* Asia-Pacific Poker Tour (APPT)
Other events may be added at the discretion of PokerStars.
When you win a satellite to a qualifying special PokerStars event and
subsequently unregister for that tournament, or you win a second entry to
the same tournament, your account will be credited with W$ that you can see
in the Cashier screen. You can then register for the special event of your
choice that accepts W$.
You can read more about T$ and W$ on this page:
http://www.pokerstars.com/poker/tournaments/
Please note that W$ cannot be used for regular tournaments, or exchanged for
T$ (Tournament Dollars). However W$ can be sold or transferred to other
players. If you have made an agreement with another PokerStars player to
sell W$, then you both will need to enter in matching transaction details in
the PokerStars client under the "Requests -> T$/W$ trading" menu. Once both
parties have entered in matching requests, the trade will be confirmed and
processed.
Please let us know if you have any questions about W$ or anything else here
at PokerStars.
Happy new year,
GustavoQ
PokerStars Support Team
W$ 
)
