Here's what's worked for me (Score 1)

As others have mentioned, the basic rule of weight loss is simply to expend more energy than you take in (eat less, exercise more). Unfortunately, that is often easier said than done. After gaining 50 lbs at a desk job, I finally started getting the eat less / exercise more bit to work and have lost 15 lbs in a month and a half. Here's the things I follow, and they might work for you, too:

• This is a lifestyle change, not a diet - That's one of the most important things to remember. Eating better (and less) along with physical exercise should represent a permanent lifestyle change. Realize up front that your doing this for the long haul.
• Keeps stats - Seriously. Monitor your weight from week to week (daily weight checks might be discouraging as your weight can fluctuate in a seemingly drastic manner throughout the week). Also monitor your food intake. Set a healthy level of caloric intake that promotes weight loss (such as around 1700-1800 calories/day for most men), and watch the calories. There are some fantastic programs out there for Pocket PCs and Palm handhelds that have great food databases for tracking intake. Best of all, if your not sure whether you should eat something or not, plug in into your program and see how it pans out with your daily caloric intake. If you haven't had much to eat during the day, you might find that you actually can have a couple slices of pizza and a beer, and still be fine. But, without measurement, you'll only be guessing.
• Ditch sugared sodas *and* fruit juice - We all know sugared sodas are nasty for you, but the level of sugar and calories fruit juice (yes, even the all natural stuff) is insanely high. Diet soda and sugarfree drink mixes (like Crystal Light), will be better in the long run. Better yet, drink water.
• Learn to love black coffee - If you don't doctor up your coffee with cream and sugar, it's surprisingly low in calories. Need something cold? Well, skip the Frappucino (it's like drinking cheesecake), and go for an iced Americano instead. Cold, highly-caffinated, and only 15 calories in a 16oz. size. Bear in mind, though, that if you're not a black coffee / espresso drinker, you'll need taste buds of steel. Also, coffee is a diuretic (sp?) meaning you'll have to pee more often. Be sure to drink more water to replace the lost fluids.
• Set an easy goal - Don't stress over something like I must lose X pounds in Y months. Keep it simple. Know where you want to be eventually, but don't set an actual time period. Instead, focus on simply weighing less each week. If you lose half a pound over a week, great. If you lose three, even better. You'll eventually get to your target weight, but don't worry if it takes a long time. The important thing is that you make progress (even if only a little) from week-to-week.
• Make beer a special treat - I love beer. I love great imported and microbrewed beers. I hate light beers, and would rather do without than drink that swill. Unfortunately, alcoholic drinks can sabotoge weight management. So, instead of giving up great beer, I just have it for special occasions, and then only when dining out. This means that I have a beer (just ONE) every month or so. I've saved money, weight, and now have discriminating taste (read: I'm a beer snob).
• Don't skip meals - If you don't eat, your body goes into starvation mode, and will try to save some of that energy that come in later in the day (translation, you're more likely to store fat). Be sure to have some kind breakfast to kick off your metabolism for the day.
• If you're expecting a big meal later in the day, adjust your intake earlier - In other words, eat even less (fewer calories) for breakfast & lunch if you're expecting a big dinner. Just be sure to eat something thoughout the day to keep the metabolism going.
• Cut down your portions. - You'll realize you need to do this as soon as you notice just how many calories can be in a normal dinner. If you're eating out, ask for a take-out box when your food arrives, and immediately store have of the dinner away to enjoy as a leftover meal on a later day.
• Don't reward yourself with food - Just finished designing a web site for a big client? Just got MCSE certified? Had a rough day at the office? Then you *deserve* to have a pig-out fest, right? NO! Don't kill your nutrition as part of a celebration. Instead, grab a new CD, DVD, or the latest toy off ThinkGeek. It'll last longer, and not force you to put on weight.
• Find an exercise that you're willing to do, and stick with it - It might take some time to find out what this is, but don't give up trying. I (like many others) went with running, and am using a simple plan devised by CoolRunning.com (Google-search Couch to 5k). My first week I felt like I was going to die. Now, six weeks in (out of nine total), I feel great. Never give up. By the way, if you get bored, try including other exercises as well, or adjust your bike/running route. Variety will keep things interesting.
• Make regular exercise a commitment - As in, plug it into your calendar, if necessary. The point is, this is something that *must* be done, and all other meetings/commitments need to be scheduled around it. We make time to get the oil changed in our cars, go to the dentist, and to back up our computer data... we should also make time to exercise so that we'll be around to enjoy the other aspects of life. (Note: although getting any kind of regular exercise at any time of the day is important, most folks do find it easier to do it first thing in the morning [and are more likely to stick to doing it]. This way it's done for the day, and you've already accomplished something before heading off to work).
• Exercise with a friend (of similar physical condition) - If someone is counting on you to be there, you might have more motivation to show up.
• Include extra physical activity where possible - This is in addition to your regular exercise commitment. Bike commuting is great, but do other things like *always* taking the stairs. Also, when in a parking lot, park farther out from the doors. You'll definately get a space more quickly, and may even get inside the building faster than if you were spending time hunting for a close spot.
• Don't eliminate things you like from your diet, find a way to factor them in. - I have Ben & Jerry's ice cream every night. But, I shoot for the lighter versions, and stick to one serving (that's 1/2 a cup). I also factor the fat & calories of that ice cream as a regular part of my daily total. It's not the most nutricious food, but it's not ruining dietary needs, either. Keeping stats (mentioned earlier) makes this easy to do.

Most of this boils down to common sense: eat less, exercise more, set easy goals, and keep measurements so that you can hold yourself accountable. Good luck.