They're probably my favorite band of all time and they're definitely THE best live act I've seen.

I don't know if you're aware of this, but they've had 3 vocalists. The best of course is Bruce Dickinson, who's responsible for most of their hits. The other two, Paul DiAnno and Blaze Bayley do not sing as well as Bruce but they were alright.

Check out these songs:
1. Hallowed Be Thy Name (their best song ever, Steve Harris could never top this epic, although he came close a few times)
2. Fear Of The Dark (listen to the live version, much more powerful than the studio version)
3. Wasted Years
4. The Evil That Men Do
5. The Trooper
6. Run To The Hills
7. Number Of The Beast (check out Bruce's scream)
8. The Wicker Man (their most recent hit)
9. Aces High
10. 2 Minutes To Midnight
11. The Clairvoyant
12. Killers (this is a DiAnno song, very nasty and evil)
13. Futureal (Blaze's song)
14. Iron Maiden (the classic, DiAnno song)
15. Wrathchild
16. Be Quick Or Be Dead

I would recommend you picking up any of their compilations. I have Best Of The Beast 2CD edition (now out of print, but if you can track it down, it is the best compilation).
Other compilations that are still available:
- Ed Hunter
- Edward The Great
- Best Of The Beast (1 CD version)

or just check out any of their live albums.