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The catch with this type of offer would be that's it's too good to be true ;)
Most (if not all) of these kinds of schemes will not offer visitors targeted to your products and services. In many cases visitors are incentivised to click for dubious reasons (such as making money for a number of websites viewed, toolbars that replace links in webpages, traffic exchange schemes and similar).
These offers can seem enticing since the costs are so low as to make many people think, what have I got to lose? But you'd be better off with 10 targeted visitors than 5000 untargeted ones.
If such schemes delivered good traffic, you would doubtless find that the cost per visitor would quickly rise to match up with genuine market value, as you might see at pay per click engines. Widget buyers come at a premium determined by how profitable a widget is.
I would strongly recommend you go either one of the traditional routes (such as pay per click search engines or some kind of established advertising network) or if this is really beyond your financial means then put in some legwork to publicise your idea yourself - find appropriate places to discuss your widget such as niche forums and the like.
Of course, the more compelling your idea (and your presentation of it), the more receptive you are likely to find potential customers and the quicker you can gain some traction. Similarly, if you can come up with a creative and unique way to promote your widget, you may find your early efforts can 'snowball' and your promotion can start to take care of itself.
Assuming the traffic actually involves humans who really see your site (by no means a given) and if you are in such a scheme for a set period, you could try heavy handed attempts to get interest in your landing page.
You would doubtless need an offer of some attention-grabbing magnitude though: "Free money and sex for every visitor!" or something like that.
