Great and very useful to me are the Hotkeys:
Hotkeys
< > for user changesets
N — on/off notes layer
D — on/off Map Data layer
G — on/off GPS tracks layer
S — on/off satellite layer (Firefox only)
H — open object history
1 — open first version of object
Z — zoom to changeset/object bbox
E — Open editor
8/9 — prev/next map position
O— open OSMCha
shift + O — open Achavi
Experimental hotkeys:
K L — navigation between changeset elements
shift + L — pan to current location
shift + H — open My changesets
Y — open Yandex.Panoramas
shift + E — open second editor