Lose It!: This site is where I log my food intake for the day. You can create an account for free, and I can sync my Fitbit up with the site, so that it automatically tracks how many calories I've burned and then it sends that data back to the Fitbit site. So, if I walk for 30 minutes and then log that I drank a coffee via Lose It, Lose It sends that data over to Fitbit and Fitbit automatically updates the pretty charts and graphs that I like looking at so much.
The reason I prefer logging my food via Lose It is because Lose It has a mobile app that I can use on my Android. And (big bonus points for this to Lose It), the app has a nifty barcode scan feature for food logging. So, if I eat a store-bought granola bar, I don't have to go to the site to type that into my food log. I simply hit the scan function and tada! Lose It grabs all the nutritional data. Way cool. Plus, Lose It makes it really easy to earn badges (I got one right away for just starting an account with them and then immediately another for syncing my Fitbit with the site). I love badges. They make me happy. It's like getting a gold star from a teacher when I was in grade school.
Earndit: This site is the primary way that I bribe myself. It rewards you not with badges, but instead with actual spendable points. Every time you log an exercise through this site, it gives you a certain number of points based on the intensity and amount of time that you exercised. Then, they have rewards you can 'buy' with your points (such as gift certificates, discounts on various products, and that type of stuff). As much as I love badges, I really like getting actual rewards that I can pick and choose myself. To me, it's like getting paid to shop (or in this case, getting paid to exercise!)