Sarevok's Tome is interesting - I like cards that can act as ramp in the early game, and provide value in the lategame. I may have to test it out, although if you aren't running other ways to venture into the dungeon, it may be too slow. I guess the baseline is 5 turns, assuming you keep the initiative and venture into the undercity every turn? Hmmm....
Venture Forth amuses me greatly. I've found it somewhat rare to get more than two casts of
Inspiring Refrain off, so may be too slow. I'll probably still try it out though - if you're looking for a long, drawn-out game, it can represent a fair amount of ramp.
edit:
Folk Hero is an okay white draw engine for tribal decks.
Black Market Connections is interesting to contrast with
Phyrexian Arena - it costs an extra life,
but you also get the card immediately. Throw in the treasure and token production, and it looks quite strong.... assuming you can afford the life cost. (edit: reading is tech >.>)
Deep Gnome Terramancer seems like an interesting hate card. As others have noted, it triggers off fetchlands, which is sort of nice. Doesn't even require your opponent to have more lands than you.