There are many variations on revenue share from the loan structures Robert mentioned to royalties to true revenue sharing agreements with lots of variations and tweaks in between. Revenue share agreements have been used for many years in the video game business. Thought about another way, percentage rent in malls is also a form of revenue shares. So are sales commissions and the fees Apple, Kickstarter, etc. get when you sell through their platforms.
VCs are not likely to do revenue shares although a few VC backed outfits will (Lighter Capital in Seattle is one). Some angels will do them - it's a question of finding angels who believe you will generate revenue, trust you to handle the funds properly, and like the idea of collecting cash without needing the company to find an exit.
You need to pay a lot of attention to structure, make sure you think about contingencies and work through the accounting, reporting and tax implications - they can get tricky.
I like revenue shares and their variations. If designed well to match the situation, opportunity and needs of the business and presented to investors who like the benefits you can offer they are a very effective way to assemble capital. I've put together at least a dozen deals along these lines over the years and have always wondered why they are not used more often.
I'd be happy to continue the conversation off-line.