The following is a guest post from Noah Kagan. Noah was the lucky winner in the OnStartups contest to win a free ticket to the 37signals sold-out master class.
Thanks to Dharmesh I was very lucky to attend the sold out 40 person class in Chicago. DHH, Jason and Ryan broke the day into 3 parts. How they worked, design theory and feedback on clients sites. 
I've NEVER gone to a $1,000 event so I was mostly curious to see who else spent that much money. The audience was comprised of aspirational entrepreneurs, a fair amount of web dev shops and even my friends at YouNeedABudget.com.
Overall, I would say it was a great experience. They even ripped apart my new site RewardLevel.com in front of the class which provided invaluable advice. Most surprising was the emphasis on copywriting over design.
I think for some in attendance it's easy to get wrapped up in the hype of 37Signals and the idea that you have to do your business like them to be successful. I think for the most part they have brought a fresh / clear attitude to building a company and learned a lot I wanted to share with you below.
38 Tweetables From 37 Signals
If you like one or more of these, you're encouraged to tweet them using the conveniently provided link.
Building Great Products
1) Always start off with what's the problem? [tweet]
2) Never go with your first instincts. [tweet]
3) Limiting yourself on tools will enable you NOT to add more things than necessary. [tweet]
4) On your webpage, reduce time spent on non-core features. [tweet]
5) The most important thing for designing is copywriting. [tweet]
6) Realize, the level of fidelity is wrong for the stage. Don't go big when all you need is basics. [tweet]
7) The product is the one with the ego. The product has to be right. Take nothing personally. [tweet]
8) Lack anything final. Design is just one battle. [tweet]
9) When you take months to do something you add months, focus on time limitations and only the core wins. [tweet]
10) Trade with people if they feel strongly about certain decisions. [tweet]
11) Real simple examples work better than marketing speak. [tweet]
12) Never do lorem ipsum blah blah. [tweet]
13) Try it and look at the data for decisions. Don't be attached to your decision. [tweet]
14) Treat all customers the same. No favoring. You never know how much they'll be worth. [tweet]
15) Set tight time frames, solve the simplest problems. [tweet]
16) Leaving software unfinished is the natural state of software. [tweet]
17) Bring out the scope hammer. Taking too long, means we are doing too much. [tweet]
18) We wrote out everything we wanted to do next year, then over lunch we killed that. Things change. [tweet]
Design Theory
19) Try to understand the difference between features and problems! [tweet]
20) Make sure you understand the problem. Ideally, its a problem you are facing yourself. [tweet]
21) What do you want me to do on this page? Focus on that. [tweet]
22) The power of 3. Keep teams small and effective. [tweet]
23) Let me make the best use of my time, don't stop me with meetings. [tweet]
24) Ask a person to draw the screen from memory and only the most important things will be remembered. [tweet]
25) Use a thick marker during design since you can only focus on the key things. [tweet]
26) We judge a lot about how good a design is by how long it takes to implement. [tweet]
27) Users always come with feedback in the form of solutions, not problems. Try to understand root issues. [tweet]
28) Everyone we hire gets screened for being a good writer, including engineers. [tweet]
29) Epicenter design. What is the most important thing on the page? [tweet]
30) Rebuild pages from the most important thing out. See where you get to the point where it gets complicated. [tweet]
31) Mobile development is great for design. Since you are limited and only put on the essentials. [tweet]
32) Copywriting is significantly undervalued! [tweet]
Random Nuggets
33) Charge from day one. If its not good enough then there is not enough value. [tweet]
34) Our whole business is beating email by an inch. [tweet]
35) Email is the most popular software application in the world. [tweet]
36) Don't use RSS readers. Go to the sites when you want. Helps focus. [tweet]
37) Short bursts of working together are more effective than full-time together in the office. [tweet]
38) The 37signals logo is a guy saying hi. [tweet]
This article was written by Noah Kagan who runs http://RewardLevel.com. A site that rewards your customers for signing up for your service. Follow him on twitter.com/noahkagan