I opened up a TD Ameritrade savings account online a couple of months ago. If you set up an automatic deposit of $100 or more a month after 12 months they give you an extra $100 (you also earn interest on this money but it's less than 1%).
My credit union offers a savings account that I never knew about (as I have just a regular savings account with them) until I was checking around on their website. You can only make two withdrawals a year from the account. You earn 5% on the first $2,500, 3% on anything between $2,500-$5,000, and 1.5% on anything after that.
So I approximate how much I will need for a vacation (I try to over-estimate) and divide it by how many months I have between now and then and that's how much I save every month.
I also charge everything on my Disney Visa so I should have a couple hundred dollars and Rewards Dollars (my Mom does this too and usually has $1,000 in Rewards dollars but they go every 2-3 years). I also do Sunshine Rewards and should have $100-$200 in Disney gift cards by my big family trip in December 2011.
I have other separate savings accounts with ING (and their measly interest rate

) for other things like taxes, car repairs, dog maintenance, Christmas/gifts, etc. It's easier to keep everything separate so I know exactly what each account is "for".
I'm going on a solo trip to WDW for a half marathon this October and I rented points so that saved me money and Kroger had a deal before Easter if you buy $45 worth of gift cards you save $5 so I bought enough to cover the rest of any expenses on that trip and probably will have some left over for the next trip.