While I'm familiar with or curious about a fair number of these, I try to be clear where my ignorance lies. Extra opinions on things that are worth getting (or avoiding) are entirely welcome.
Stuff I Have
Song of Ice & Fire RPG: I have this in hardcover and I'm still tempted to get the PDF for two reasons, one good and one not so good. The good reason is that the noble house creation rules in this game are awesome, maybe even better than Birthright. It's good enough that it can be ported out of the setting if need be, but then the setting is so magnificent, would I want to? The less good reason is that the hardcover was extensively errata'd, and the PDF is (i presume, since GR is good about such things) updated, so you can skip the hassle.
Artesia: The worst thing I can say about this in PDF is that the book is even more lovely. Still, the book is also quite large and dense (and also quite good - it's numerous Ennie nominations were no fluke) and probably crosses that invisible threshold where havign a PDF to reference really improves things. For me, the big takeaway from this game (besides the amazing art) was a really fantastic tarot-influenced system for character elements.
Battlestar Galactica: This one is worth noting as it's a very good deal. MWP books tend to have very high production values and, in turn, pretty high price tags. At $10 bucks, this is a good way to satisfy your curiosity, and the Cortex system is light enough that the book is mostly setting. That said, it's a tough sell: BSG is so much its own story that it's really hard to come up with a meaningful story of your own within its context, and the RPG has to wrestle with that. There's not quite enough information about the worlds of BSG for a pre-cylon game, but there's too much for a post-cylon game, if that makes any sense. The level of data is tuned more towards what you'd need if you were going to do your own version of the series.
Demon Hunters: A somewhat tongue-in-cheek modern day monster hunting game, it really gets more points than anything else for both being quite funny and also quite playable.
Fading Suns: Holy crap, Fading Suns! I love Fading Suns! Er..ahem, I mean, that's an excellent game to see on the list. It's mashup of Dune and Warhammer 40k makes for a fantastic sci-fi-with-dark-but-not-Chthulu-overtones that's possibly my favorite Sci-fi RPG ever. The mechanics are interesting, and occasionally inspired (the paired stats are brilliant) but it's really all about the setting.
Geist: Totally worth it. The NWoD books just keep getting better, and Geist (the kind-of new Wraith) is mechanically clever (best powers system I've seen since the original idea for Mage/Ars) and with a very playable setting that steps away from a lot of familiar tropes while embracing others in ways you might not expect.
Grimm: Confession - I bought this and still haven't done more than skim it. I bought it purely on the strength of the REALLY, REALLY fantastic D20 minigame of the same name that this is based on. From flipping through, it has a fudge-like dice system, and it has much of the same dark fairy-tale wonder that I bought it for. I'll say its worth it, just based on the amount I've seen, but take that with a suitable grain of salt.
Hero 6th Bundle:
Mouseguard: This is profoundly worth it. Not only is it a fantastic game, but because of its format (the game is square) the PDF is very screen readable.
Mutant & Masterminds, 2nd: This is pretty much the modern standard for supers (HERO sort of having become more its own thing) and even though I own it in hardcover, it's tempting to get a PDF just for reference.
Starblazers Adventures: Fate in space, but not just any space: Crazy, wahoo british comics space. Like Hero, this is a worthwhile PDf investment because the book is just so damn big.
Stuff I Want
Deadlands Reloaded: Ok, it's Deadlands, and that's kind of a selling point or not, simple as that. My brother's a big fan, but I've never tried it before. Since this is the Savage Worlds version, I'm willing to make the plunge, if only because I'm also curious about the Savage Worlds part of it.
Dragon Warriors: I never played the original, but I did read a lot of the very enthusiastic gushing when this came out. I guess it's new-old-school or something? Honestly, I'm nto totally cure, but it inspires enough passion that I'm curious.
Legend of the 5 Rings, 3rd ed: So, there's some loyalty here. I've always liked L5R, but I walked away after picking up Second edition and feeling like I got something dirty on my hands. That's left me hesitant to pick up 3rd because on one hand, the game really did need revising, but on the other, if it was more revisions along the line of 2nd, then that would be worse than nothing. But the books were pretty, very very pretty, and at this price point I think I'll finally take the risk.
Mutant City Blues: Superheroic police procedural using gumshoe? Hard to say no.
Pirates of the Spanish Main: Pirates in Savage Worlds. I really have no further explanations except to say those are two great tastes that taste great together.
Dark Conspiracy: Oh, man, there's a blast from the past. I remember the adds for this when it came out. For some reason I even remember reading an adventure for it. Modern day conspiracy and magic in the shadows. Classic stuff, though I'm not sure what it offers beyond nostalgia at this point.
Etherscope: I've seen this game around from time to time, and it looks full of steampunkey goodness, but I've never had a reason to quite make the leap to pick it up. I still don't, but at this price point I'm curious.
Heavy Gear: Man, I have always been curious about heavy gear. It promises fun, fast mech combat, and the brains behind it have demonstrated an ability to come up with really neat, interesting ideas, but It's never been quite enough to grab me.
Iron Kingdom's Character's Guide: I'm torn on this. I really DESPISED the Witchfire Trilogy, the d20 adventures that introduced this setting, but the art and setting information was all pretty neat and darkly steampunky + D&D. Friends have spoken well of it, but that initial hatred was pretty strong. Hmm.
Judge Dredd: So, it's Judge Dredd. That's one of those selling points that either ha already made the sale, or lost it. admit, for me, it's lost it, but that's not reflection on the product.
Monte Cook's Arcana Evolved: I don't doubt this book is worth the price, but it's like being offered a computer that's a few years out of date. It's a great deal, but will you use it? I probably won't.
Twilight 2000 and Twilight 2013: Another nostalgia trip. The Durham 3 piqued my curiosity by digging this one out for some actual play, but i think I'll let this particular sleeping dog lie.
The City of Brass: On one hand, I love planar cities. On the other, I have enough Planescape material to crush a cat. I'm not really sure what this offers, bu tit definitely looks interesting.
No Freaking Clue
Cooper's Compendium of Corrected Creatures (Bundle): I got nothing.
DragonMech: Cool title, certainly
Dungeon Crawl Classics #51: Castle Whiterock:My keen deductive skills suggest this is an adventure.
Megatraveller bundle, Mark Miller's Traveller and TNE-0302 Traveller: THE New Era DELUXE Package: I'm not a Traveller guy, but if I was, I imagine this would be pretty sweet.
RunePunk: Another cool title
Ultramodern Firearms d20: Something to do with guns, I presume