Connections for Arduino Uno/Nano
OV7670 connections:

VSYNC - PIN2
XCLCK - PIN3 (must be level shifted from 5V -> 3.3V)
PCLCK - PIN12
SIOD - A4 (I2C data) - 10K resistor to 3.3V
SIOC - A5 (I2C clock) - 10K resistor to 3.3V
D0..D3 - A0..A3 (pixel data bits 0..3)
D4..D7 - PIN4..PIN7 (pixel data bits 4..7)
3.3V - 3.3V
RESET - 3.3V
GND - GND
PWDN - GND

1.8" TFT connections:

DC - PIN8 (5V -> 3.3V)
CS - PIN9 (5V -> 3.3V)
RESET - PIN10 (5V -> 3.3V)
SPI data - PIN11 (5V -> 3.3V)
SPI clock - PIN13 (5V -> 3.3V)
VCC - 5V/3.3V (depending on jumper position on the TFT board)
BL - 3.3V
GND - GND


Connections for Arduino Mega
OV7670 connections:

VSYNC - PIN2
XCLCK - PIN9 (must be level shifted from 5V -> 3.3V)
PCLCK - PIN12
SIOD - PIN20-SDA (I2C data) - 10K resistor to 3.3V
SIOC - PIN21-SCL (I2C clock) - 10K resistor to 3.3V
D0..D7 - PIN22..PIN29 (pixel data bits 0..7)
3.3V - 3.3V
RESET - 3.3V
GND - GND
PWDN - GND

1.8" TFT connections:

DC - PIN48 (5V -> 3.3V)
CS - PIN53 (5V -> 3.3V)
RESET - PIN49 (5V -> 3.3V)
SPI data - PIN51 (5V -> 3.3V)
SPI clock - PIN52 (5V -> 3.3V)
VCC - 5V/3.3V (depending on jumper position on the TFT board)
BL - 3.3V
GND - GND