Your voice sounds a bit better [I think fuller] in stereo, whether you're adding narration to your home videos/slideshows, doing a video blog or podcast, using something other than the mic built into your webcam.
Depending on how far you want to dive into the subject, how much time, effort & cash you want to invest, you can find lots of info Googling on "bootleg recording microphones", where they use mic cartridges rather than the normal, large mics you're probably used to seeing. Alternatively you can use something like these cheap mics, some with Sony logo, that you can find at various Asian on-line retailers & on eBay. [Note, I've no idea if some or all of the Sony branded mics are knockoffs, seconds, reman, or the original new -- a while back I downloaded the *manual* from Sony, & it was a PDF of a poor scan of the typical, very poor, very sparse Chinese instruction sheet included with Very cheap products.]
http://www.meritline.com/electrets-condenser-stereo-microphone---p-82233.aspx
Amazon comparison
http://www.amazon.com/Sony-ECM-DS70P-Electret-Condenser-Microphone/dp/B00006HOLL
Using *Any* sensitive mic you have the problem that sound can travel through the stand or holder & through the microphone casing/housing -- use a rigid stand on your desk & the mic will pick up the sound of you setting down a pen or coffee cup, which is why they use boom mic stands in a radio station for example. Whether you make your own setup out of a couple of cartridges, buy one of the cheap stereo mics I linked to, or buy an expensive mic, unless it comes with some sort of spider cage, anti-shock mount, you've got to figure out a way to try & isolate it from physical shock & vibrations.
While it would probably work well enough just suspending, handing it from a wire, & I'm sure many people will come up with better designs/ideas, I built a cage mount of sorts, epoxying hooks inside a small tin can [around the circumference top & bottom], then stringing rubber bands between them. I then took a small, plastic prescription bottle/container, drilled a hole in the bottom, then mounted/glued the jack from a cheap Y cable to that hole. That container fits up through the center of those rubber bands -- the overall effect is similar to a bobble head.
The 2nd problem you'll encounter is because mics take/need power to work well. The mic jack on your PC/laptop supplies power, ground, & receives the signal, which works fine with a mono mic using the usual 3 part mini-jack. With 2 mics [right/left] you need at least one more line or connection to receive the 2nd signal -- or you can use the Sony-type mic [or a DIY pair of cartridges] with a battery box. At the bottom of this page is a simple schematic to make one -- if you can solder you can put this together. http://suite101.com/article/use-a-battery-box-with-plug-in-power-microphones-a140741
I found out about the battery box thing after buying one of these stereo mics on a whim because of the low cost, finding it only worked mono plugged into the mic jack, taking it apart a couple times etc. -- now just run a cable from the battery box out to the line-in on the PC... line-in records stereo, whereas the mic jack only does mono, but line-in does not supply the needed power.