Personal opinion but...
White
Mobilization
Exalted Angel
Akroma's Vengeance
Oblation
Weathered Wayfarer or True Believer
Astra Slide (unc)
Green (too many to choose from)
Ravenous Baloth
Hystrodon
Silvos
Gigapede
Silklash Spider
Naturalize (common)
Krosan Tusker (common)
Black
Oversold Cemetary
Grinning Demon (although I'm not really a huge fan)
Undead Gladiator
Rotlung Reanimator
Entrails Feaster
Smother (unc)
Red
Blistering Firecat
Goblin Sharpshooter
Words of War
Goblin Piledriver
Starstorm
Lightnig Rift (unc)
Blue
Future Sight
Read the Runes
Voidmage Prodigy (snooze)
Standardize (well, I like it a lot)
Quicksilver Dragon
Complicate (unc)
Land/Arts
Fetch Lands are all good
Grand Colloseum
Contested Cliffs
Slate of Ancestry
Some of the unc creature-type lands are good too
What I think will be sleepers and/or go up in value pretty substantially with time:
Menacing Ogre
Gigapede
Undead Gladiator
Words of War (someone will break it)
Entrails Feaster