Yesterday I found this great book about Web Applications Development, written by 37signals (don't you think that the creators of Basecamp know a little about Webapps?    )

photo credit: chelseagirl

Here's the listo of the chapters titles:

1. Introduction
2. The starting line
3. Stay lean
4. Priorities
5. Features selection
6. Process
7. The organization
8. Staffing
9. Interface design
10. Code
11. Words
12. Pricing and signup
13. Promotion
14. Support
15. Post-launch
16. Conclusion

As you can see, the book provides information from everything about creating a webapp, from the start to the end of the process.
You can read it free online or buy a PDF or printed version. A must read!