Here's another tip that I learned about recently. I'm very allergic to spider bites and swell up really bad. So, one day, I had about 8 bites and they were all itching badly. I went to my handy, dandy search engine and started reading away about home remedies.
What works for me is to make a paste of baking soda and water. Spread the paste onto the bites (works for mosquito or spider bites) and let it stay on for at least 15 minutes. I do this at night after the kids are in bed. After the 15 minutes, wipe it off. In the morning, the swelling has gone away and so has the itching.