以下是50个电子书网站的列表：
1. Project Gutenberg
2. ManyBooks
3. Free-eBooks.net
4. Smashwords
5. BookBoon
6. Feedbooks
7. eBooks.com
8. Open Library
9. Google Books
10. Amazon Kindle Store
11. Barnes & Noble Nook Books
12. Kobo
13. Scribd
14. Bookyards
15. FreeTechBooks
16. FreeComputerBooks
17. Online Programming Books
18. FreeBookSpot
19. Library Genesis
20. Ebookee
21. Ebook3000
22. GetFreeEBooks
23. Librivox
24. Audible
25. Audiobooks.com
26. Hoopla
27. OverDrive
28. OneClickDigital
29. BookRix
30. Blurb
31. Lulu
32. Smashwords
33. Wattpad
34. FictionPress
35. Bookrix
36. Booknode
37. BookLikes
38. Bookish
39. BookBub
40. BookPage
41. BookBrowse
42. Book Riot
43. Bookforum
44. Booklist Online
45. The Millions
46. Goodreads
47. Shelfari
48. LibraryThing
49. Riffle Books
50. Bookish.com
请注意，某些网站可能需要付费才能访问其电子书库。