I really love stock sites like iStockPhoto. I’ve purchased almost a hundred images.
During SXSW, an article was published about Twitter’s main homepage image being stock, with some pretty heavy faux outrage about how this is bad. Horrible, off topic headline. First off, the author doesn’t differentiate between spec and stock. Stock = 100 people can buy the same image. Spec = 100 custom images are created, one is paid for. That is just sloppy journalism. Twitters use of stock isn’t unethical at all, but one could argue with the mass pile of cash they have raised, $1000 for an illustration should have been on the list of purchases.
Second, if you use stock for your startup, just remember that there is a downside: other people can use it too.
Twiter.com (notice one t) is a squatter looking to cash in on the misspellings:
See that birdie? Same as the Twitter homepage. And they can do that legally because it was a stock image, which is still on sale today.
Stock sites are great resources for ideas and simple images. Be careful not to rely on them too much. And if you do, send a big thank you to the designer when you make it big.