If you're looking for a new idea for your guild to try, try a private guild auction. My guild started doing this and it has been a huge success from the very beginning. At first we started doing auctions on Sunday evenings...but it was so popular, we are now doing it on Thursday evenings as well. Here's the high level:

(1) Designate a trusted officer to be the auctioneer; this person will receive all goods to be auctioned
(2) Designate a trusted officer to be the accountant; they are responsible for collecting funds (and dispersing funds...more on that later)
(3) A guild with helpful guildies who are willing to help the guild by donating items to be auctioned

What happens in the guild members donate items to be auctioned. They can request that 25%, 50%, 75%, or 100% of the proceeds of the auction go to the guild, the remaining fund to the player. This way, the donation not only helps the player, but also helps the guild. Bids are made in 100 gold increments to keep it simple (although obviously expensive stuff might start at 1,000 gold or higher). The auctioneer accepts bids and announces "going once", waits 20 seconds, "going twice", waits 10 seconds, "sold". This keeps downtime to a minimum.

Stuff that auctions well includes crafting materials, recipes, motifs, and gear. But really anything can be sold at auction. Stuff that receives no bids is either sent back to the player donating it or is put in the guild bank for a later auction.

You can modify the guidelines as you see fit, they are not stead-fast rules. I hope you find this event as enjoyable as our guild has - it's a blast!