Authorship of various works is ascribed to sage agastya. Here is an attempt to list such works, based on details furnished by mahAmahopAdhyAya rA satyanArAyaNa and Prof. Nanjundayya of Mysore University. Most of the works seem to be available in print or as manuscripts, except for those related to shilpa shAstra.
Works on shrIvidyA:
1. agastya sUtra
2. tripurasundarI stotra
3. pa~nchadashI mantra vyAkhyA (shrutisamuddhR^ita shrIvidyA TIkA)
4. shrIvidyAdIpikA
5. purashcharaNa paTala
6. yogamInAkShI stotra
7. yogoddhAra chakrabhAvanA
8. shakti sUtra (not the same as agastya sUtra)
9. saubhAgya kavacha
Other Works:
1. agastya gR^ihyasUtra
2. agastya paTala (jyotiSha)
3. agastya prakAsha saMhitA
4. agastya vAstu shAstra
5. agastya vaidya
6. agastya shilpa shAstra
7. agastya shrautasUtra
8. agastya saMhitA
9. agastyAShTaka
10. atharvaveda kalpasUtra
11. chitrAgastya (shilpa shAstra)
12. dvaidha nirNaya
13. agastya nATya shAstra
14. pa~nchapakShi shAstra
15. pravarAdhyAya
16. maNi lakShaNa/ratna parIkShA
17. shivabhakti vilAsa
18. sakalAdhikAra
19. shivAdhikAra
20. sudarshana kalpa
Miscellaneous works:
1. kArtikeya stotra
2. gaNapati stotra
3. goShThIshvara stotra
4. dashAvatAra stotra
5. lakShmI stotra
6. vedapAda stave
7. shiva stuti
8. shiva stotra
9. shivAShTaka
10. sarasvatI stotra
11. mahAsudarshana kavacha
12. ekAdashamukha hanUmat kavacha