The Bar is no longer open to the public, but a privilege granted only to those who have made a purchase from Baen.com and who choose to exercise that privilege. Previous users active in the last 12 months have been grandfathered in. We have added a tipjar, so that you do not even need to buy a book, merely contribute something to the maintenance of the Bar.
The tipjar is located at baen.com, which makes sense both because it needs to be available to people who are not yet registered participants here, and also because that's the site that is in the business of selling, handling money. Type in tipjar (one word) in the search function at the top of the page, and up it pops.
Be sure to use the same email account to make your tip/purchase as the one you want to have credited with it on the Bar.