Think you need a business plan to have a successful website/web service? The statistics would actually indicate otherwise, as the most successful websites were from people who were able to ship a product out of the door for an audience to start using and then iterate upon.
This is what I keep hearing like a broken record from people who know what it takes to make it work online. Are you worried about having all the features your clients might ever want? You are going about it completely wrong, what you should be doing is focusing on key features that work – and work really well. Beyond adding clutter and delaying your launch, feature bloat can actually detract from whatever primary pain point your service is supposed to alleviate.
Pick the top 3 or so features that are core to your service working and make sure that the value of each feature is incredibly clear so that a user has no doubts at all as to WHY your service exists in the first place. If a customer can’t quickly identify the value in your service then all is lost anyway.
Link > Plan
So if you axe the business plan and try to not over think your new service, how are you supposed to go out and try to acquire funding for your start-up? Y Combinator jokingly says that they value a company by “adding 500k in value for each engineer and subtracting 250k for each MBA” because investors today want to see progress on an idea, not just a bunch of words around how good an idea might be. So what do investors care about these days instead of just a business plan? A link to a (mostly) working product that has a little bit of traction in the marketplace. The cost barrier to entry for a new web service has been lowered to much that investors need to see this level of success before investing because they have the luxury of being more picky.