I always do everything I can think of to help our vacation account along:
Market Research groups (in-person)--they generally pay $75-$125 for a couple hours of time. Look for firms in your area and get into their database, and then they'll call you when they have a study you might qualify for.
Credit card rewards--I use a combo of our cash back card, a card that lets us get gas gift cards, and the Disney Visa depending on who gives us the best reward. We charge everything (including utilities, food, etc.) and pay it off at the end of the month. This usually adds a few hundred dollars to our fund.
Online surveys--they don't pay alot, but every bit helps
Mypoints & Ebates--Ebates gives you cash back for online purchases, and Mypoints gives you points for purchases and reading emails, fulfilling special offers, etc.
Test drive rewards, when possible. Just found out about one today for a $50
Best Buy gift card. It won't help with a Disney trip, but it will buy us a few things we ordinarily don't splurge on.
Opening bank accounts--fairly often I get offers for $50-$100 for opening new bank accounts. I don't always do these, but if the terms are right I will.
Cleaning my office--My DH and I clean my office twice a month and make an extra $100. It only takes 45 minutes (no bathrooms or kitchen) and it's a pretty easy way to make extra money.
That's all I can think of at the moment, hopefully this will give someone some new ideas.