You can check out a draft of the list I'm working on here:
http://cubetutor.com/viewcube/13664
There's some mistakes in there, so not every card is actually supposed to be there, but you get the idea. There is a theme for each 2 color pair:
UW - blink/etb
BW - sacrificing your own stuff
BU - faeries and ninjas
RU - instants/sorceries matter
RB - hellbent/madness/discard
GB - graveyard matters
GR - ramp
WR - battalion/anthem/weenie
WG - tokens
UG - +1/+1 counters
In each color, there are 3x commons, 2x uncommons, and 1x rares.
My list isn't quite where I want it to be, but I think you want a relatively clear strategy for each color. To me, I don't think "library manipulation" is a clear enough strategy. While you want the cards to be useful outside the color pair, you also need the cards to come together into a strategy that can win.
As far as ideas for shards, here's some alternate ideas that could could do instead of what I have above:
Esper:
WU - you got this one
UB - mill, cipher/combat damage matters (could also work in rb)
BW - life gain/payment, constellation/enchantments matter (esp. if you have heroic as a theme elsewhere)
Jund
BR - "there will be blood" (blood lust, blood rush, combat damage matters), sacrificing your stuff
RG - suspend, storm, domain, big creatures/5+ power matters
GB - sacrifice (I really think GY is the best choice)
Grixis
UB - see above
BR - see above
RU - artifacts matter, storm, suspend
Naya
WR - radiance/color matters, tokens, soldier tribal
RG - see above
GW - you got this one