iOS installing apps without app store [closed]
Apple supports "Ad-Hoc" application distribution for exactly this purpose, but it is limited to 100 devices. If you have an Enterprise developer account, you can do Ad-hoc distribution within your organization, as well.
iOS Developer Distribution Options
iOS Developer Enterprise Program
You need to apply for a Enterprise/Corporate development license with Apple. Then they provide the option to deploy without the app store.
The minimum amount of employees is high though (about 500 I think). EDIT: The employee restriction has been removed!
See this link for more info: http://developer.apple.com/programs/ios/enterprise/
Yes, ahdoc distribution allows you to installed on upto 100 devices (including the ones you use for development), all you have to do is have the paid for developer account (the standard $99 one).
Here's one explanation, but there are loads of articles around on the subject:
http://furbo.org/2008/08/06/beta-testing-on-iphone-20/
Update Summer 2013: The limit now seems to have been increased from 100 devices to 200 devices.