Have you got Mew?

[Pidgey_Six]

To do this the glitch way, you can not have fought the Gambler outside the Underground Tunnel leading to Celadon or the Youngster with a Slowpoke you find after Nugget Bridge.
Step 1: Save outside Underground tunnel that goes from Lavender to Celadon.
Step 2: Take 1 step down and push start before the Gambler sees you.
Step 3: Fly to Cerulean. Your start button will not work.
Step 4: Go up Nugget Bridge and into the bush-maze. Fight the Youngster with a Slowpoke.
Step 5: Fly to Lavender and go through the west exit. Your start menu will pop up. Cancel it with 'B'.
Step 6: You will randomly encounter Mew after you close the start menu. It will be at Lv.7 and will know Pound. Catch it!

[Bruninho]

To do this the glitch way, you can not have fought the Gambler outside the Underground Tunnel leading to Celadon or the Youngster with a Slowpoke you find after Nugget Bridge.
Step 1: Save outside Underground tunnel that goes from Lavender to Celadon.
Step 2: Take 1 step down and push start before the Gambler sees you.
Step 3: Fly to Cerulean. Your start button will not work.
Step 4: Go up Nugget Bridge and into the bush-maze. Fight the Youngster with a Slowpoke.
Step 5: Fly to Lavender and go through the west exit. Your start menu will pop up. Cancel it with 'B'.
Step 6: You will randomly encounter Mew after you close the start menu. It will be at Lv.7 and will know Pound. Catch it!

Oh I remember when I first got this code last year, I was so surprised that it actually worked! Until then I always thought Mew only appeared in the cartoon/anime

[Mikachu Yukitatsu]

I sent my Pokémon Red to the other side of the World, ILikePokémon;P in Australia and got it back with two Mews in it. That was 2003 if I remember correctly.