Mini-sites come in different flavors but all have one significant element in common. Each site is very tightly focused upon selling a single product or service. No Flash. No graphics. No links out. No banners or advertising of any kind. Nothing that detracts from site purpose, which is to make sale.
The Pure Definition
In simplest form a mini-site consists entirely of a sales letter and order form. That is, your visitor either buys or clicks Back button. Your site offers no other option.
Suppose your current site is focused on selling ebooks and software to help people raise their kids. Each product is a candidate for a mini-site dedicated entirely to selling it.
You might do well with, "How To Build A Sewing Site," or anything specific of interest to some. Maybe show how to remodel your kitchen, build a plane or boat. But a mini-site dependant upon keywords such as "site design" or "site promotion" isn't going to make it because there is simply too much competition.
In some cases, pre-selling your visitors before sending them to sales pitch on an affiliate site can work wonders for your conversion ratio. In others, you're better off simply generating a click to site.
If pre-selling is a good idea for a program that is paying well, then a mini-site consisting of only a page or two can work well. You may need only your enthusiastic endorsement of product on a single page. Or you may want to add another providing an in-depth review. All content points to links to sales pitch on program's site.
This works, but as above, major task is in drawing targeted traffic. If this can be managed, then this is also a good model.
Selling Hot Products
To take notion of selling as an affiliate program one step further, you may want to consider selling currently hot items. For example, back up a couple of years and anticipate interest in MP3 soon to burst upon scene. Make right pick, find best affiliate program, and you may have a winner.
This approach works only for those who already know how to sell most anything. Without a background in selling effectively, particularly on Web, it's best to leave this notion to those who do.
Profits To Be Expected
Your purpose in building a mini-site is to generate profits. However, you are not looking to make a living off site. Quite contrary. You simply want to generate a separate income stream. And $200/month may be all you need. Given one such site, trick is to continue producing others, adding to total income with each.
Claims Of Time
In notes about building mini-sites, one claim made often really bothers me. That you can toss such a site together in an hour or two. This is not even close to feasible for most.
Pros may be able to quickly gather parts of existing sales pitches with information from affiliate program or manufacturer of product. Then, in short order, cobble together a sales pitch that works at least reasonably well. Still, I don't know anybody who really can manage this in an hour.
To me, time is part of cost equation. It takes time to put together a slick sales presentation. More to define an advertising campaign. And even more to track costs versus results.
Generating Hits Is The Hard Part
Okay. You've got a good product, a neat sales letter, and an order form. All is looking good. Now how do you draw targeted traffic to read your pitch? This is critical issue, for profits depend upon success in doing so.