Michael Pollard's Personal Website

 

Woot!
Woot! is the first "deal of the day" format site I became familiar with. Woot! offers one item each day, and when that item sells out, that's it for the day. The exception to this is the occasional (and unannounced) "Woot-Off" when after one item sells out another item is put up in its place. The Woot-Off is also the only time the percentage left of an item is provided. Quantities are always a maximum of three, and shipping is always $5 per order, no matter how large or small the item. Yes, a 60" TV will ship for $5. Even three 60" TVs will ship for a total of $5. The item changes at midnight Central Time.
Items are usually technological in nature, or otherwise catering to tech-savvy people. Product descriptions are usually humerous and do not necessarily reflect the item itself, though full product specs are also given below the description.
In addition, Woot! has several related sites, Shirt.Woot!, Wine.Woot!, and Sellout.Woot!. Sellout is actually a partnership with Shopping.Yahoo!; the initial page is hosted by Yahoo!, and the page redirects back to Woot! for further details and actual purchasing. The items are similar to the main Woot items, and sometimes they are interrelated.
The forums on the Woot! sites are very helpful with comments and criticisms of both the items and the prices. Note that some terms in the posts get substituted, some to remove bad language, some to remove over-used terminology. When WootOffs come up, the site Bags of Crap is helpful with reviews and comparisons as well as estimates of quantity and sellout times. A more useful item on a daily basis is Wootalyzer (see below).

Silver Jewelry Club
This one isn't a "deal of the day," but a "deal of the fifteen minutes." Silver Jewelry Club actually offers free silver jewelry. Or as their promotions say, "Free Sterling Silver with real Gemstones, no catch, no gimmicks, no obligation". Four items are available at a time, and each item is only up for fifteen minutes (with a countdown timer listed by each item).
The items are 92.5% pure silver, well-crafted, unique designs, and each includes a "gift pouch", a small drawstring mesh bag. Most items also have gemstones. They aren't expensive stones, but they are real semiprecious stones and they look nice. These are great gifts for the guys... girls don't have to know they were cheap, and they don't look cheap.
The only catch is $6.99 shipping and handling per item. And you can add a chain, also sterling silver, to any pendant for $4 in your choice of 16", 18", or 20" lengths. Well, you might also consider that rings are only available in a single size at a time as a catch.
Why do they do this? Because they have a full-line catalog available at Peora.com, and this is inexpensive publicity. Postage doesn't cost much (they just mail the items), and the raw materials don't cost much; as I write this, silver is only 18¢ a gram. And you can take advantage of their self-promotion. Just try to keep yourself from paying $50 for a ring in the catalog because you like the design but the free one's not in your size...
As a note, the items are made in the USA at their own facility in Los Angeles.

 

Thing Fling is also a deal-of-the-day type of site, though the deals frequently come more than once a day. As with many of the other sites I list, the items are generally technically-oriented or oriented to those who are. Unlike most sites, they sometimes have items that are free (not including shipping). Shipping is a flat $6 for the first order of the day and $4 for the second, with a maximum shipping cost of $10 per day. That means that if the third order is a free item, it's completely free, since you've already maxed out your shipping costs. Some items are also "loss leaders". That is, it costs them more to sell them than you pay. The "free" items are a good example, but they also sometimes have items for 99¢ that will cost more than $6 to ship.

They also have very good customer service. Unlike many sites like this, if you get something that is broken or has missing parts, they will do their best to make it up to you, whether that means replacing the item or giving you a refund or coupon for the item. Some report that a small item was missing from a set, and they were given a coupon for the full value and were allowed to keep the stuff besides.

DOD Hero does things a little differently. They don't charge shipping (because that's more "heroic"). They usually have one item a day, changing sometime after 9PM EST, and it's usually some small gadget. I've gotten a mini tripod, 3/16"-3/32" headphone adapters, and mini dice from them. They also sometimes have gag items (defensive weapons...) like fart bombs and trick gum...

Wootalyzer
This is actually a tool, not a site. Wootalyzer provides a small toolbar that lists a large number of deal-of-the-day sites, with the picture, title, price, and time left, with one-click buttons for viewing the full description or buying the item. In addition, you can set up alarms for various things, such as WootOff items on Woot or a Mystery Box on Thing Fling. (I'd recommend turning off the siren alarm for each WootOff item and turning the volume down for the others...)
While Wootalyzer does not allow adding new sites or new keywords to watch for, those features can be difficult to implement in software. They do offer a very large number of sites as it is, unfortunately. I say "unfortunately," because I have found several good ones and have bought a lot more than I intended to. I have found several good sites here, and I have bought items from several of them including Thing Fling and Yugster.

As I see it, the more "deal-of-the-day" sites, the better. If one doesn't have an item I want, maybe another one does. Though that can be hard on the checking account.

Some sites tracked by Wootalyzer: