We're a sporting club which has an equipment (camping, climbing, hiking gear, etc) hiring module built within a ruby-on-rails web-app.
The rails site is undergoing the final stages of completion, and this requires some final touches on the equipment-hiring portion of the site.
These largely consist of data-validation additions/changes, and some supporting user-interface changes.
Our current 'real-world' requirements are that a member can be hired equipment (eg. 1 x small tent, 2 x sleeping mats, etc). A deposit for these items is calculated based on what's been borrowed, and a 'hire fee' is collected at the time of hiring based on the number of weeks someone is hiring equipment for.
The deposit and hiring fee are generally set based on pre-entered rates, however can be overridden at the time of hiring equipment out.
An 'EquipmentLoan' record is saved with a date of hire, date due (when it should be returned), and associated items are saved in 'EquipmentLoanItem' records.