From GameOver

Firmware for the iPhone and various iPod families including the Touch can be found in the XML file provided by Apple at iTunes Firmware Versions. Restore versions are used for full restores and updates, while update versions are capable of updates ONLY.

Manually selecting a firmware file

Select the iPhone in the Devices list on the left and go to the Summary Tab inside the device (this is usually the default screen). While in iTunes hold down the Options (some people say it is Alt) key for OS X or the Shift key for Windows while clicking on the "Check for Update" or "Restore" button to open a file browser window where you can select a firmware you manually downloaded.

Direct Download Links

These links are provided for your convenience and were obtained from the above url.

iPhone	Release Date
1.1.4 (4A102) Restore 1.1.3 (4A93) Restore 1.1.2 (3B48b) Restore 1.1.1 (3A109a) Restore 1.0.2 (1C28) Restore 1.0.2 (1A543a) to 1.0.2 (1C28) Update 1.0.2 (1C25) to 1.0.2 (1C28) Update 1.0.2 (1C27) to 1.0.2 (1C28) Update 1.0.1 (1C25) Restore 1.0 (1A543a) Restore	February 26, 2008 January 15, 2008 November 11, 2007 September 27, 2007 ** August 21, 2007 August 21, 2007 August 21, 2007 August 21, 2007 July 31, 2007 ** June 29, 2007 **
iPod Touch
1.1.4 (4A102) Restore 1.1.3 (4A93) Restore 1.1.2 (3B48b) Restore 1.1.1 (3A110a) Restore 1.1 (3A101a) Restore	February 26, 2008 January 01, 2008 November 11, 2007 September 27, 2007 ** September 10, 2007 **

 ** Note **
 The actual reference to this firmware has been removed from the iTunes Firmware Versions page,
 but the direct download links still work.