In case anyone wanted the images for all the early unlocks. Arcane missiles is from Illidan. 2x Wolfrider from Lorewalker Cho, 2x Polymorph from King Mukla, and 2x Reckless Rocketeer from Helmet Nestingwary.
You can also mouse over the progress bar when you have your class deck selected. It'll tell you what the next reward will be. For Paladins at level 28, it's a gold Blessing of Might. I suspect the level 30 reward is also going to be a gold Blessing of Might (if the pattern holds true as the other classes).
Warrior: 32 - golden warsong commander 34 - golden warsong commander 36 - golden fiery war axe 38 - golden fiery war axe 40 - golden cleave 41 - golden cleave 42 - golden kor'kron elite 43 - golden kor'kron elite 44 - golden whirlwind 45 - golden whirlwind 46 - golden shield block 47 - golden shield block 48 - golden arcanite reaper 49 - golden arcanite reaper
Updated the post to here, thanks guys. Not missing too many more now, hopefully have a full list of leveling rewards soon :D Once it's finished I'll pretty it up so we have a great resource for new players.