I thought I'd start a collection of identification guides others have pointed me toward.

Moved into a wiki format here: https://forum.inaturalist.org/t/observing-identifying-wildlife-wiki/

FLIES
https://sites.google.com/view/flyguide

CATERPILLARS
https://www.fs.fed.us/foresthealth/technology/pdfs/Caterpillars_of_Eastern_Forests.pdf

CLEARWINGS (Hemaris)
http://www.silkmoths.bizland.com/Sphinx/bshthysbe.htm
http://mothphotographersgroup.msstate.edu/species.php?hodges=7854

GRASSES
https://forum.inaturalist.org/t/how-to-identify-grasses/8538/3

TREE OF HEAVEN v WALNUT v SUMAC
(vid) https://www.youtube.com/watch?v=4BA5Dec3_8o

HICKORIES
http://bioimages.vanderbilt.edu/pages/compare-hickories.htm

ASHES
http://www.treeremoval.com/ash-tree-identification-guide/#.XYLP0ChKg-V

FUNGI
(vid) https://www.youtube.com/watch?v=LKF_pIY0Zpc

MICROORGANISMS

https://diatoms.org/genera/pinnularia

https://www.biodiversitylibrary.org/item/23616#page/7/mode/1up

https://www.uwsp.edu/cnr-ap/UWEXLakes/Documents/programs/convention/2018/WedPM/GinaLaLiberte_BlueGreenAlgaeinWI.pdf

not available online, but useful for ID of genera https://books.google.ru/books/about/Freshwater_Algae_of_North_America.html?id=yjnLAwAAQBAJ&redir_esc=y

Tips'n'tricks
http://www.cassisaari.com/inaturalist-tips-tricks/

iNat Features
https://forum.inaturalist.org/t/list-of-inaturalist-org-features-wiki/28939

Identotron
https://www.inaturalist.org/observations/identotron?observation_id=10306875
i.e. plug "/identotron?observation_id=" between observations and id# in the url

Use Identify to annotate
https://forum.inaturalist.org/t/using-identify-to-annotate-observations/1417

Takes for Novices
https://forum.inaturalist.org/t/list-of-inaturalist-org-features-wiki/28939

A Guide to Guides [guides are deprecated but this is still handy]
https://forum.inaturalist.org/t/a-guide-to-inaturalist-guides/950

Search Urls
https://forum.inaturalist.org/t/how-to-use-inaturalists-search-urls-wiki/63

How many / how big pics
https://forum.inaturalist.org/t/photo-number-photo-resolution-per-observation/6049

Placeholders & opt-outs
https://www.inaturalist.org/observations/6150336#activity_comment_3310978

Linking observations
https://forum.inaturalist.org/t/using-the-field-similar-observation-set-for-linking-observations-of-lepidoptera-when-raising-on/1018

Animation and video
https://www.inaturalist.org/projects/animated-observations