I recently implemented a Paypal Community Pool into one of the communities I run which is 100% donating driven. I have to tell you that it has been quite successful so far and we are collectively able to pay for a few months into the future.. If you have a paypal account, it takes about 5 minutes to set it up.
After setting it up, simply create a broadcast email to all of your members and let them know what you are pooling money for and include the link. I also shortened the link so that I could track how many clicked but didn't contribute so that I can modify my message the next time I remind them. Also remember to add a button to your sidebar or footer for members to make a contribution on the fly.
BONUS TIP FOR ADDING THE BUTTON:
When you add your link, add class="button" to the code like so:
<p><a class="button" href="http://yourpoolurl" target="_blank">Donate to Community Pool</a></p>
A couple of features that I especially like about this:
Contributors can leave a comment with their donating....great for community and for thanking contributors
You can upload a cover photo to your pool.
Members feel secure about making a donation
Contributors can only use Paypal and so those who need to use a credit card will still need to use another method. If you have trouble with this one ask and i have some other solutions for that.