Lazarus IDE Shortcuts
All shortcuts can be edited in Environment / Editor Options / Key mapping. See Key Mapping.
Mac OS X
Mac OS X has quite different key policies. For example most F keys are used by the OS, there are no menu Alt shortcuts and there are large guidelines (contrary to linux and windows where only a few keys work the same under all programs).
The apple human interface guidelines for key bindings can be seen here: 
Here is the list with the conflicts of the default lazarus key mapping:
[Cmd]-F keys. A few F key combos are free, but this seems to depend on version and layout. So better not use them. (conflicts: F3 find next, Shift-F3 find previous, Ctrl-F8 jump next error, Ctrl-Shift-F8 jump previous error, F5 add breakpoint, Ctrl-F4 close file, F11 toggle OI, Ctrl-F12 view units, Shift-F12 view forms, F12 toggle unit/form, Ctrl-F11 open project, Shift-F11 add unit to project, Ctrl-Shift-F11 project options, Ctrl-F9 build, F9 run, F7 step into, F8 step over, F4 run to cursor, Ctrl-F2 stop program, Ctrl-F7 evaluate, Ctrl-F5 add watch, F1 help, Ctrl-Shift-F1 help editor)
[Shift]-Up,Down,Right,Left - move cursor Alt-[Shift]-Left/Right: jump to next word Alt-Up/Down: jump to start/end of paragraph (conflict: find declaration) Cmd-[Shift]-Left/Right: jump to start/end of line (conflict: jump next word) Cmd-Up/Down: jump to start/end of file (conflict: scroll one up/down) Cmd-Shift-Up/Down: select to start/end of file (conflict: method jump)
Cmd-?: show context help
Delete/Backspace: delete char [Shift]-PageUp/Down: jump page up/down
Home/End: jump to start/end of file (conflict: jump to start/end of line)
Cmd-[Shift]-Tab: switch application (conflict: jump prev/next file) Cmd-Alt-D: show/hide dock Cmd-Ctrl-D: dictionary Cmd-*-Space: spotlight, apple reserved Cmd-Alt-Escape: force quit Cmd-A: select all Cmd-C: copy Cmd-E: find word at cursor (conflict: incremental find, solved) Cmd-F: find Cmd-Alt-F: incremental search Cmd-G: find next (conflict: goto line) Cmd-Shift-G: find previous (conflict: insert guid) Cmd-[Alt]-H: hide app (conflict: jump back) Cmd-M: minimize window Cmd-Alt-M: minimize app Cmd-N: new file Cmd-O: open file Cmd-Q: quit (conflict: goto line) Cmd-Shift-Q: log out Cmd-S: save Cmd-Shift-S: Save As (conflict: save all) Cmd-Alt-S: Save All Cmd-V: paste Cmd-W: close window (conflict: word completion) Cmd-Shift-W: close file Cmd-Alt-W: close all files Cmd-X: cut Cmd-Z: undo
Control: The control modifier is used by cocoa in text fields. So it is free for designer and source editor functions.
Control-1-9 create special chars on some layouts (conflicts: bookmark commands). Cmd-*-1-9 apple functions like capture screen (conflicts: bookmark commands).
Here are the XCode shortcuts: