Decluttering techniques for the clutter challeged

I have a confession to make - I am not a neat person.  Clutter seems to spring up around me in record time.  Give me a clear, flat space, and it will be filled within days.  Despite that (or maybe because of that?), I love the feel of a neat, picked up house with open spaces. I've recently been focusing on reducing the amount of stuff in my house, which is helping me more often have the clean feeling I desire.  Here are some of the techniques I've recently found useful in my efforts to fight clutter - I'd love to hear other people's ideas as well!

• Devote an hour or three on Saturdays to uncluttering:  There are many techniques for picking up and decluttering your house.  Some people suggest picking one thing a day to get rid of, but I've found that to be ineffective - I need to get into a grove to really get things done.  Recently, I've been dedicating every Saturday morning that I don't have other plans to this.  In reality, this means one or two Saturday's a month I spend at least half an hour on declutting.  I set myself a minimum of 10-20 things depending on what section of the house I'm tackling, and don't stop until I've found that many items that I no longer use and can be donated.  Sometimes I'm have to stretch to reach my goal, but other times I get in a groove and look up 3 hours later with multiple bags ready to go out of the house.
• Don't try to sell things to recover cost: For more expensive items, I had a hard time getting rid of them because I knew they retained value, and I didn't want to throw that money out the door.  However, I never found time to actually find a new home for them, so I wasn't benefitting from getting them out of the house, AND I wasn't benefiting from extra money from selling them.  I've since decided to simply donate any and all items to Goodwill - it's a great organization so I know I'm helping others in need, it's a simple 5 minute drive from my house to drop stuff off, and it means I actually get things out of my house shortly after identifying them.  For those in a high tax bracket, the tax deduction for donations also can be a significant fraction of what you might get from selling them, and when you factor in time spent trying to sell and coordinate with buyers, you may in fact come out ahead.
• Go through categories several times a year: There are a lot of things I haven't used in a long time, but still believe I'll use again.  This is especially true of clothes, such as those that can't be used during the current season so I have an excuse for not using them.  Rather than trying to push myself to get rid of things I'm not ready to, I simply try to do a pass every couple of months.  I often find that Items that I wasn't quite ready to let go of previously are easy to donate the next pass I make.
• Rewarding yourself is ok: While it may seem counterproductive, rewarding yourself with something new can be a great way to reduce the amount of stuff in your house.  Some of my most successful unclutting weekends have been when I've set myself a goal and reward.  For example, I had been thinking about getting a Glassybaby for a while.  However, the console table where it would go best was covered with stuff.  I told myself that I could get one if I cleared the table and took at least 3 grocery bags full to Goodwill - I ended up with 7 bags and 3 clear surfaces!  I now have 2 beautiful Glassybabies flickering with candlelight on the table beside me as I write this.
• Don't be afraid of getting rid of things you may want again:  If the cost of replacing something is low and / or the likelihood of needing it again is low, it may be better to be rid of the item, enjoy the space, and pay the cost of replacement if you ever find yourself wanting it again.  Books are one of the main sources of clutter in my house - I love to read, often browse bookstores and come home with something new, and don't like to get rid of good books because I often re-read my favorites.  However, I have enough "favorites" that the likelihood of rereading any one book in the next 1-5 years is fairly low.  While I now buy most books as ebooks, I still end up with a number of "real" books, and have many favorite series still in book form. For me personally, I find I value the space more than the cost of replacing the book.  I've compromised by keeping only the first book in each series - if I ever do decide to re-read them, I can buy (or borrow from the library) the rest in ebook form.  This is the best compromise for me, since it still leaves me with a bookshelf of favorites, but I no longer have to keep overflowing bookshelves throughout the house.

What other uncluttering techniques have people found useful?