Rounds of golf have been very popular and are easy to get. A round for 4 at a very nice course with a cart has gotten as much as $180 for us. Most courses are more than willing to donate, too.
Jewelry goes well. I contact people who sell it through at home parties, like Lia Sophia. They often have extra samples or can purchase items themselves at cost and are willing to donate. That goes for people who sell candles, Tupperware, purses...I collect business cards when I go the the ENDLESS rounds of those types of parties and then hit them all up in January, before our auction in April. (Ummm, I've been know to book a party out of guilt/gratitude, so be careful).
If you can find a donor, power tools have always gone over very well. I was shocked, our first year, when a repiprocating saw went for $200!! We've lost our contacts for those kinds of things, though, sadly.
This year, we did "Make A Day of It" packages for several small towns within 30 miles of where the auction is held. We asked lots of merchants in those towns to make small donations ($10 - $15 in value) and then grouped them together. The idea was that gift certificates would tempt people to visit those towns and "Make a day of it" there. The small gifts and merchandise that we got helped to make a nice display. We attemped to get overnight stays at hotels or B&B's in each community, but were'nt too successful with that.
This year we had an in-homewine tasting for 16 (with 24 bottles of wine) donated by a liquor store. It had tons of bids and went for about $250.
We also had an in home cooking lesson provided by a caterer. It was also very popular.
We have a group of artists (They are the art/design department of the company a friend works for) who pick a theme each year and then each create something connected to that theme; maybe a painting, maybe a sculpture, maybe something they have built. This year the theme was gardens and the stuff was amazing. High quality paintings, sculpted garden art, someone even put togehter a kitchen garden with live herbs. I was pissed when I got out bid on that at the last minute! Sometimes one bidder will try to get ALL of the related items.
I always get one of the better great strides premiums so I can auction it. This year we got two flip cameras. In the past it's been the nice fleece or the digital camera.
Tickets to the ballet, symphony, theater, outdoor music festivals are easy to get andget decent bids. I try to get gift certificates to restaurants that are near those venues and put them together as "date night" packages, but this is hit or miss.
Hope this helps! I spend from Jan 1 - mid April gathering donations. I start with letters to my warm contacts and then add about 100 or so cold contacts. I have a good group of people who also ask thier contacts for things. It's a lot of work, but it's usually worth it. This year's auction had 55 items and raised over $4,000.
Good luck. Don't be afraid to ask if you have questions about setting up the auction process (bid sheets. check out, etc.) I'll be glad to try to help!