Let's face it---with the iPhone's limited 148 application capacity and lack of the ability to hide the icons of native apps you aren't using (on a non-jail broken device), adding speed dial icons may not be your top priority. But if you value the opportunity to add truly customizable speed dial icons, then One Tap Dial is the app for you.
Whether you want to create speed dial icons for the few people you call or text the most, or an entire page of icons for work groups, One Tap Dial allows customization and functionality that I have not found with other similar applications. I really wanted the ability both to use custom photos for the icons and to personally name them, which One Tap Dial allows. The application basically uses Safari to run a local script that triggers the call or text when the created icon is tapped. The developer notes that your contact information is not sent to the One Tap Dial server or anywhere else, a concern users had voiced after using the app.
Setup is very intuitive, allowing you to create a custom icon from your contacts list or de novo. There is a built in list of generic icons included with the app, but the great part about One Tap Dial is that you can use photos from your Contacts or Photo Library to personalize your icons. When creating each icon, you choose what function will be triggered by tapping it, namely 'call', 'text' or 'ask'. You can name each icon whatever you want as well. Once created, you cannot edit an icon but rather have to make a new one and delete the old. Also, the actual One Tap Dial application needs to stay on your phone for it to work---I put it out of sight on my last page of apps since there's no way to hide it.
You can use One Tap Dial to create an unlimited number of personalized call or text icons for your iPhone. It definitely does lag a little over the native phone or contacts apps when placing a call, but it's not interminable and I don't find it bothersome. I have always found the app to be stable as well. One Tap Dial hasn't been updated in months, so what you see is probably all you'll get (despite the website's claims). Well worth $0.99 in my opinion.