Below are some language-specific charts of special characters. If there are important characters I've missed, please let me know.

Esperanto

	Capital			Small
Description	Char	Hex	Escape	Char	Hex	Escape
C-caret	Ĉ	108	Ĉ	ĉ	109	ĉ
G-caret	Ĝ	11C	Ĝ	ĝ	11D	ĝ
H-caret	Ĥ	124	Ĥ	ĥ	125	ĥ
J-caret	Ĵ	134	Ĵ	ĵ	135	ĵ
S-caret	Ŝ	15C	Ŝ	ŝ	15D	ŝ
U-breve	Ŭ	16C	Ŭ	ŭ	16D	ŭ

Irish, Gaelic and Welsh

	Capital			Small
Description	Char	Hex	Escape	Char	Hex	Escape
A-acute	Á	C1	Á / Á	á	E1	á / á
E-acute	É	C9	É / É	é	E9	é / é
I-acute	Í	CD	Í / Í	í	ED	í / í
O-acute	Ó	D3	Ó / Ó	ó	F3	ó / ó
U-acute	Ú	DA	Ú / Ú	ú	FA	ú / ú
A-grave	À	C0	À / À	à	E0	à / à
E-grave	È	C8	È / È	è	E8	è / è
I-grave	Ì	CC	Ì / Ì	ì	EC	ì / ì
O-grave	Ò	D2	Ò / Ò	ò	F2	ò / ò
U-grave	Ù	D9	Ù / Ù	ù	F9	ù / ù
W-grave	Ẁ	1E80	Ẁ	ẁ	1E81	ẁ
Y-grave	Ỳ	1EF2	Ỳ	ỳ	1EF3	ỳ
A-circumflex	Â	C2	Â / Â	â	E2	â / â
E-circumflex	Ê	CA	Ê / Ê	ê	EA	ê / ê
I-circumflex	Î	CE	Î / Î	î	EE	î / î
O-circumflex	Ô	D4	Ô / Ô	ô	F4	ô / ô
U-circumflex	Û	DB	Û / Û	û	FB	û / û
W-circumflex	Ŵ	174	Ŵ	ŵ	175	ŵ
Y-circumflex	Ŷ	176	Ŷ	ŷ	177	ŷ
B-dot	Ḃ	1E02	Ḃ	ḃ	1E03	ḃ
C-dot	Ċ	10A	Ċ	ċ	10B	ċ
D-dot	Ḋ	1E0A	Ḋ	ḋ	1E0B	ḋ
F-dot	Ḟ	1E1E	Ḟ	ḟ	1E1F	ḟ
G-dot	Ġ	120	Ġ	ġ	121	ġ
M-dot	Ṁ	1E40	Ṁ	ṁ	1E41	ṁ
P-dot	Ṗ	1E56	Ṗ	ṗ	1E57	ṗ
S-dot	Ṡ	1E60	Ṡ	ṡ	1E61	ṡ
T-dot	Ṫ	1E6A	Ṫ	ṫ	1E6B	ṫ
long r	--	--	--	ɼ	27C	ɼ
long s	--	--	--	ſ	17F	ſ
long s-dot	--	--	--	ẛ	1E9B	ẛ
Tironian et (7-agus)	--	--	--	⁊	204A	⁊

Czech and Slovak

	Capital		Small
Description	Char	Escape	Char	Escape
A-acute	Á	Á / Á	á	á / á
A-umlaut	Ä	Ä / Ä	ä	ä / ä
C-caron	Č	Č	č	č
D-caron	Ď	Ď	ď	ď
Dz	DZ Dz	DZ Dz	dz	dz
Dz-caron	DŽ Dž	DŽ Dž	dž	dž
E-acute	É	É / É	é	é / é
E-caron	Ě	Ě	ě	ě
I-acute	Í	Í / Í	í	í / í
L-acute	Ĺ	Ĺ	ĺ	ĺ
L-caron	Ľ	Ľ	ľ	ľ
N-caron	Ň	Ň	ň	ň
O-acute	Ó	Ó / Ó	ó	ó / ó
O-circumflex	Ô	Ô / Ô	ô	ô / ô
R-acute	Ŕ	Ŕ	ŕ	ŕ
R-caron	Ř	Ř	ř	ř
S-caron	Š	Š / Š	š	š / š
T-caron	Ť	Ť	ť	ť
U-acute	Ú	Ú / Ú	ú	ú / ú
U-circle	Ů	Ů	ů	ů
Y-acute	Ý	Ý / Ý	ý	ý / ý
Z-caron	Ž	Ž	ž	ž

Acute = čárka, caron = haček, circle = kroužek. For tall letters, haček (caron) often appears as an apostrophe on the right (an indivisible part of the letter).

The digraph "ch" is treated as a single letter, lying between H and I alphabetically, and sorting accordingly (for instance, in dictionaries and name lists). But it is spelled with two letters, as in English. Dz and dž are also commonly spelled with letter pairs.

Polish

	Capital		Small
Description	Char	Escape	Char	Escape
A-ogonek (tail)	Ą	Ą	ą	ą
C-kreska (acute)	Ć	Ć	ć	ć
E-ogonek	Ę	Ę	ę	ę
L-slash	Ł	Ł	ł	ł
N-kreska	Ń	Ń	ń	ń
O-kreska	Ó	Ó / Ó	ó	ó / ó
S-kreska	Ś	Ś	ś	ś
Z-kreska	Ź	Ź	ź	ź
Z-kropka (dot)	Ż	Ż	ż	ż

Polish alphabet:
a ą b c ć d e ę f g h i j k l ł m n ń o ó p r s ś t u w y z ź ż ch ci cz dz dzi dź dż ni rz si sz szcz zi