Ha, I got 1870 and my OTB rating is 1861
How accurate is this ELO estimator?

Yeah, I got 1705 when I took it. I don't think I'm quite at that level based on my ratings on this site, but my chess strength increases dramatically as the time control increases so who knows. 5 minutes per move is much longer than I get for live games here so it makes sense that I'd perform better.

2120... There's no telling whether it is correct, but it might be. If this is an over estimate by 200 points, I'd believe it. I haven't played a USCF tournament game in 5 years, so my official USCF rating is 1569 and I was gaining over 200 points per year in each of the two years I played in tourns.

I got like 1860, I'm about a 1400 here on site, but with the time to think on each diagram, I can see why it over shot it. I think the best way to make it more accurate would be to make each individual diagram be separate, and have a timer on them to ensure that only five minutes was spent. I have no idea how long I took on each individual one.

I think it is inflated by around 250 points but no more.
You might take a moment to read about how Elo ratings are calculated.
This site relies on the fact that most people have no idea how they work and don't know about statisitcal pools.
Your rating is based on other players in the pool. Different pools can net different results.
For example, lets say you are a pretty good player in a pool where most of the other players barely know how to play. Your rating will be at the higher end of the scale.
Now, if you play in a pool of players who are mostly masters, your rating will be at the lower end of the scale.
And these 2 numbers would be totally different.
That site has NO pool of players. They have just created fixed values based on puzzles or positions from players who were probably in the same pool like FIDE our USCF.
The only way to know for sure what your rating would be in FIDE or USCF would be to play in official tournaments.
http://www.chessmaniac.com/ELORating/ELO_Chess_Rating.shtml
For those of you with an official OTB rating, I would greatly appreciate it if you could take this quick rating test. Obviously this isn't the best way to figure out your rating, but I'm not able to play in any tournaments right now so I'd like a rough estimate.