1. Bemani maps (MEGA) link
2. FunOrange's on-the-fly map stat changer
3. Clean up osu! song folders (bg's etc.)
4. Webpage with a list of links to various tools
5. osusearch.com
6. bloodcat
7. Higu's Jump Training
8. Google docs - Jumps
9. Google docs - Short Streams
10. Google docs - Singletap
11. Google docs - Streams
12. beatmap packs
13. Piotrekol's collections editor for recovering beatmap db with collections
14. BPM Changer
15. osuskinner
16. osuMissAnalyzer
17. osuReplayAnalyzer
18. osu! Multi commands (lobby creator can use)

Other stat tracking sites:

1. osu!track
2. osu!stats
3. osu!skills
4. osu!chan
5. pp+
6. ppaddict
7. osu-pps by grumd