We could add a huge list of Anime Streaming sites, but its better off to make you choose the one you need using:
The Anime Index, a HUGE list of sites, categorized in Languages, Sub/Dubs and more.
Nyaa (Torrent) - The Best Public Tracker to get Anime from.
The Anime Index (DDL / Torrent) - This site also has Download sites/apps for Anime/Hentai/Manga and more.
AnimeTosho (Torrent) - Collates Releases from Public Trackers, and has DDL links for file attachments (Subtitles, Fonts, Chapters, Tags).
AniDex (Torrent) - Alternative Tracker to get Anime from, A Few Releasers post exclusively here.
Tokyo Toshokan (Torrent) - A Library for every type of Japanese Media, shared with Torrents.
Nibl Bots | AniMK (XDCC) - Sites indexing IRC Bots where you can Download from using IRC Clients.
Check the AnimePiracy Wiki for a detailed guide into XDCC.
A Certain Smoke's Index - A big list of the best Releases for Anime (by Seadex).
A Certain Fansubber's Index - Another list of the top Quality Releases for Anime.
The AnimePiracy Wiki - Comprehensive information about everything Anime Piracy. A MUST READ if you are interested.
AnimeThemes | Themes.moe | Openings.moe - A huge collection of Ending/Opening Themes for Anime.
The Anime Scene Search Engine - Reverse image search engine for Anime.
Taiga (Windows) | Trackma (Linux) - Automatically detects the Anime Videos you watch on your PC and synchronizes your progress with AniList, Kitsu, MyAnimeList and more. A must have for Weebs.
Senpai.moe | Monthly - Calender for upcoming Official Anime Releases.
BECAUSE.MOE - Search engine to find streaming services that offer the Anime you search for. Accurate up to May 27, 2020.