If you decide to gamble and stay, then ensure a lawyer to have a look at the paperwork. I can recommend one in downtown SF (email me). When I was in similar situation 5 years ago, this guy helped me for $1oo! :)
Question is why founders unable to raise money??? Today it is extremely easy to attract VC/angel money!
If founders are unwilling to accept new money because of greed, valuation too low, contingencies, etc... then yes maybe it is a fair gamble to work for equity... Like if you knew your startup had 99% chance of being acquired in 3 month at 5x over today's valuation, then equity pay makes sense.
However, it does not seem like the case here. Highly likely that all VC/angels had passed,.. hence, follow the money and look for an exit.
To make it easier to decide: ask founders to explain why they cannot raise money. If they bring low valuation as an excuse, ask to show termsheets and make judgement upon that. If they cannot provide this proof - run.
With or without whitespace - after gzip the difference is only about 1% or so. Bundle your js files together. Place script tag in the end of your html doc to allow parallel downloads.
I actually applied with a similar idea to summer batch and didn't get through. I think YC doesn't consider this viable.
Besides, Google is probably going to be the one to dominate the space with their $700M ITA acquisition from last summer (the deal was cleared by court a month ago). Watch this video:
http://www.google.com/press/ita/
There won't be any "facebook killer", instead the entire social netowrking buzz will gradually cool off over time. Facebook will remain the center piece "hub" of social networking, while audience interest will shift towards niche sites and apps, and most of them will be heavily integrated with / rely upon fb's api...
Take the same approach as grubwith.us and groupon did, avoid the PayPal risk.
However, if you believe there's a significant advantage of having PayPal (doubt it), then you may want to consider setting up an eBay store and handle all payments for reservations through BINs on ebay pages... vayable.com would then become a "wrapper" around your ebay store. Additionally if you get significant traction, you may get $10-40 for every person who registers with ebay through your links.
Mturk manuals are junk and very hard to follow. HIT data cleansing is the biggest issue. Instead of using the command line tool, use their API to integrate into your app, as it will save plenty of time down the road...
To "weed out" ineligible workers, try this approach:
1. Post a bunch (1000-5000) of cheap multiple-choice HITs.
2. Allow no more than 10 hits per worker.
3. Each hit to get 3 responses from different workers.
4. Review answers, compile the list of "good" workers, blacklist the "bad" ones.
5. Post another bunch of HITS, make them available for eligible workers only (found in step 4), this time the HITs might be more demanding, individually review results for each worker -> the best ones go on your "preferred worker" list.
6. Repeat steps 1-5 as necessary.
From then on it's fairly safe to rely on mturk workers from your preferred list.
Go with the smaller/safer one first and roll it out asap (2-6 months), then move on to the higher risk/reward venture. This approach will help you negotiate better terms with vc backers.
Otherwise, if you start out with the "bigger" venture first and fail, then it might be too late to go with the smaller venture idea since the void in the niche can be filled by someone else by that time...