Syntheses of best ideas, including trends, could be on the blog as well as sent as a monthly newsletter.
Hold a monthly competition for best ideas in different topics, perhaps with cash or donation prizes.
Google Now makes suggestions to you based on your calendar, map, e-mail and other sources. Popular Science Innovation of the Year 2012 http://bit.ly/JGbaWa
An analytics review at the World Bank showed that nearly a third of PDF reports are downloaded zero times. Another 40% fewer than 100 times. WaPo Wonkblog http://wapo.st/1kRWb7r
People are submitting ideas to many sites, but nowhere are the ideas rolled up into on "my great ideas" capacity. XMLRPC. (Suggested in user feedback).
Rank good ideas by "top rated" and "recent", but also offer a "stars" category which allows people to buy stars for placement (similar to bidding for Google AdWords placement).
Springwise provides a database of over 5000 innovative business ideas. Access is $400 / year. http://bit.ly/1lIx3Ay
Betterific offers a web-wide service where consumers can make suggestions to improve products and services. http://betterific.com/