You've got a sweet idea, a solid business plan, and market opportunity a plenty. So why can't you get an investor excited about your start-up?

While there's obviously a million possibilities (flame retardant firework gloves just won't sell outside the South), it's worth considering where your start-up fits in the types of businesses investors say they want to fund - and then tweaking your pitch to match. It's no secret that green businesses, as well as the technology and life sciences industries, are red hot right now. But there are other general "themes" that VCs look for in start-ups that can be useful for an entrepreneur to know.

To wit: this week Media Kitchen hosted a venture capital conference where a group of major investors talked about the "themes" their firms are currently interested in. TechCrunch listened, and relays some of the important concepts that popped out.

Here's a few: the continued personalization of content, advertising, and marketing, as well as companies that can do something useful with the influx of data and media that's become available from groups like the 80 million users on Facebook. Similarly, they're interested in the growth of mobile Web—not the half-baked version currently available on most cells.

Other hot themes VCs have an eye out for include businesses that are involved in one-to-one commerce, start-ups that merge cyberspace and real space (although I for one would like Second Life to remain in cyberspace), and global web growth. They also say they're interested in start-ups that make web search and interfaces easier and more intuitive.

Whew.

While all that's very interesting, here's the take-home message: if your start-up falls under the umbrella of one of these themes—even tangentially—info like this can help you make your pitch more attractive to an investor, and can help you get a foot in the door. What this isn't is a hard-and-fast guidebook to what VCs want. Trust us, if you show up on their doorstep with world's first perpetual motion device, they won't turn you away because it doesn't have anything to do with making the web easier to use. Unless you look like him: