If you are integrating your website with payment gateways, then you might have faced about https image merchant banner uploading. All payment gateways are using HTTPS secured protocol to process the payment. And if you want to add a banner at your payment processing system with the gateway, you'll need a secured image link. The popular Moneybookers or PayPal both are using same way too.
If you don't have HTTPS support, or don't know how to configure your server with HTTPS, then you have an option as alternate. The site http://www.sslpic.com/ Used to upload images, and provide you a HTTPS link for free. You can easily take the service from the site, and set a merchant banner without any trouble.
SSLpic - Free SSL Image hosting for PayPal.
After uploading the image, they will send you the image link at your email address. Also they are supporting tracking about the image, so that you can track how many times the image were viewed from your payment gateway. Its really nice to have such kind of service for free.
By the way, I hate PayPal myself. It's fucking stupid site with having very poor quality of customer service. I've lifted all my USD from paypal, and only kept my shit on there.