Flickr, the popular online service for the storing and sharing, offers users to test "Flick Pro" (3-month free trial), which allows unlimited downloading of photos.
This trial offer is available upon connecting to your Flickr account, and allows you, in addition to unlimited download of photos (max 50MB per photo) to benefit for the other features of the Pro formula:
Access to your photo gallery without limitation
Publish photos over 60 groups
Download original photos in high resolution at any time
Load and watch HD videos
All these features are normally charged $24.95 per year: this trial offer allow users to test the features of the pro version before considering an upgrade.