I know a lot about thrash metal. I've found some bands already that sounds like Megadeth, but I wanna find more bands. You got some which you think is a LOT similar to Megadeth?

Rattlehead, Slivers and ummm... not sure there are many Megadave clones around, unfortunately.

Old Metallica, for riffs anyway.
He played in them.

DeadxheaD. I don't care for them personally but the sound is very similar, especially the vocalist who does a dead-on "Mustaine with a Russian accent."

Do you want the thrashier Megadeth or the more melodic ones?

Portuguese band Demon Dagger's first album "Aftershock" reminds me a lot Megadeth from Countdown to Cryptic. I would say ripoff sometimes... listen for yourself:

http://metal-archives.com/release.php?id=17115

Swedish Ice Age is pretty much like Megadeth.

Agree with DeadXheaD, though while they're good its such total Megadeth worship you might as well just listen to Megadeth, only noticable difference is quality.

That's exactly how I feel. Every time I've heard them, for the first twenty seconds I was thinking, "Alright, pretty good Megadeth worship!" And after that I was thinking, "Man, I'd really rather be listening to 'Peace Sells.'"

Yeah. Deadxhead was godamn similar to Megadeth actually! A LOT! Thanks for recommending it, or whatever you wanna call it. It wasn't bad either. Much better than Memorain at least. The vocalist in Memorain only sings in the same tone all the godamn time! It gets so boring. Deadxhead however have a lot of more variation in their music. I'm gonna check out Demon Dagger. Sounds a little interesting. Wouldn't say Rattlehead is so much like Megadeth however.

http://www.myspace.com/exzeltic - Dublin thrash sound like peace sells era Megadeth.

Bitter End's only album sounds exactly like Megadeth. As with others in this thread, I am making no statement on its quality.

Try croatian thrashers Sufosia: http://www.myspace.com/sufosia

I was listening to some Egypt (UK) today, it sounds like Megadeth, but not to the point of sounding like a cheap clone and they retain some originality. The only thing I didn't like about it is that the lyrics have nothing to do with Egypt.