Is it possible to purchase a game for someone else via direct purchase or something like a gift certificate? I would love to put a handful of games on a "wish list" that I could distribute to friends and family so they can get me something fun for birthdays or holidays.

Yeah you can. At the checkout screen, you will see a box below your items that says 'Select to gift this order'. Enter the recipient's email; alternatively you can enter your own. It doesn't matter, the gift code (a string of numbers and letters) can be used by anyone who's gotten hold of it.

One thing you'll want to take note of is that all the items in your cart will be assigned one gift code, so if you want to gift specific items to multiple people, you should add only the items you want to gift for one of the intended recipients, checkout, acquire gift code email (or send over gift code email, depending on whose email address you typed) then repeat the entire procedure for the remainder of the recipients.

One thing that would be nice was if GOG sold "anonymous" gift codes. You know, so you could buy a code for $9.99 worth of GOG games, but not have it linked to a particular game.

Since GOG still doesn't have neither public profiles (so you can see which games someone owns), nor public wishlists (so you can see which games someone would like to own), this would eliminate the risk of buying a game for someone that they either already have, or have no interest in.

Regarding the gift card thing, people can vote for it here: http://www.gog.com/wishlist/site/gog_gift_card_redeem_1_or_more_games_of_599999xxx_value

True, I didn't think of that.