Here you can find the direct links to all iPod Touch Firmware Files for every released model.

1.1 (1G): iPod1,1_1.1_3A101a_Restore.ipsw
1.1.1 (1G): iPod1,1_1.1.1_3A110a_Restore.ipsw
1.1.2 (1G): iPod1,1_1.1.2_3B48b_Restore.ipsw
1.1.3 (1G): iPod1,1_1.1.3_4A93_Restore.ipsw
1.1.4 (1G): iPod1,1_1.1.4_4A102_Restore.ipsw
1.1.5 (1G): iPod1,1_1.1.5_4B1_Restore.ipsw
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2.0.0 (1G): iPod1,1_2.0_5A347_Restore.ipsw (Only purchase through iTunes)
2.0.1 (1G): iPod1,1_2.0.1_5B108_Restore.ipsw
2.2.0 (1G): iPod1,1_2.2_5G77_Restore.ipsw
2.2.0 (2G): iPod2,1_2.2_5G77a_Restore.ipsw
2.2.1 (2G): iPod2,1_2.2.1_5H11a_Restore.ipsw
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3.1.2 (3G): iPod3,1_3.1.2_7D11_Restore.ipsw
3.1.3 (3G): iPod3,1_3.1.3_7E18_Restore.ipsw
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4.0.0 (2G): iPod2,1_4.0_8A293_Restore.ipsw
4.0.0 (3G): iPod3,1_4.0_8A293_Restore.ipsw
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4.0.2 (2G): iPod2,1_4.0.2_8A400_Restore.ipsw
4.0.2 (3G): iPod3,1_4.0.2_8A400_Restore.ipsw
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4.1.0 (2G): iPod2,1_4.1_8B117_Restore.ipsw
4.1.0 (3G): iPod3,1_4.1_8B117_Restore.ipsw
4.1.0 (4G): iPod4,1_4.1_8B117_Restore.ipsw
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4.2.1 (2G): iPod2,1_4.2.1_8C148_Restore.ipsw
4.2.1 (3G): iPod3,1_4.2.1_8C148_Restore.ipsw
4.2.1 (4G): iPod4,1_4.2.1_8C148_Restore.ipsw
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4.3.0 (3G): iPod3,1_4.3_8F190_Restore.ipsw
4.3.0 (4G): iPod4,1_4.3_8F190_Restore.ipsw
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4.3.1 (3G): iPod3,1_4.3.1_8G4_Restore.ipsw
4.3.1 (4G): iPod4,1_4.3.1_8G4_Restore.ipsw
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4.3.2 (3G): iPod3,1_4.3.2_8H7_Restore.ipsw
4.3.2 (4G): iPod4,1_4.3.2_8H7_Restore.ipsw
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4.3.3 (3G): iPod3,1_4.3.3_8J2_Restore.ipsw
4.3.3 (4G): iPod4,1_4.3.3_8J2_Restore.ipsw
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4.3.4 (3G): iPod3,1_4.3.4_8K2_Restore.ipsw
4.3.4 (4G): iPod4,1_4.3.4_8K2_Restore.ipsw
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4.3.5 (3G): iPod3,1_4.3.5_8L1_Restore.ipsw
4.3.5 (4G): iPod4,1_4.3.5_8L1_Restore.ipsw
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5.0 (3G): iPod3,1_5.0_9A334_Restore.ipsw
5.0 (4G): iPod4,1_5.0_9A334_Restore.ipsw
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5.0.1 (3G): iPod3,1_5.0.1_9A405_Restore.ipsw
5.0.1 (4G): iPod4,1_5.0.1_9A405_Restore.ipsw
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NOTE : Thread will be updated as new Firmware Versions & Models came out