Quote from Mr_You:
Just to clarify...
The free EOD data is available via the Kinetick connection. This does not include intra-day tick data.
The free intra-day tick data for FUTURES ONLY is available via Ninja Traders Download Replay Data utility menu option. This data is available for Market Replay only.
You can not use the intra-day replay data for historical backtesting. The only way to get free historical intra-day tick data for backtesting is to signup for a 30-day demo with Zen-Fire or another provider.
Please someone correct me with specifics if I'm wrong.
Quote from NetTecture:
This is factually wrong. Trades often get cancelled. How do you deal with this?
I collect NxCore / Nanex tapes and I can generate the historical result in any way I want (with or without cancelled / changed trades).
Simple historical tick databases have an issue here. SOmetimes the ticks DO change.
Quote from mgabriel01:
Do you share it?
On top - these files are use4less without the software and the software is not integrated with any package I know except TradeLink. API is C only (C# wrapper avilable) and it is not easy to process nearly half a gigabyte of data 
Quote from biba4:
You can find inexpensive tick-by-tick data with bid/ask values at the time of the transaction on Kibot.com web site.
Free historical tick data going back to 2009 is available for some instruments: historical tick data for stocks.