All of these formats can be used as format strings with many dot.net framework functions (System.String.Format, StringBuilder.AppendFormat, etc...)

Base decimal value: 321543.23
Base Int32 value: 321545
Base DateTime value: 9/22/2014 6:10:45 AM

Note that some of these formats behave differently when grouped with other formats.
For example, notice the difference between {0:g} and {0: g gg}

Print formats

321543.23 - Currency: {0:c} $321,543.23
321543.23 - Currency with 4 decimals: {0:c4} $321,543.2300
321545 - Decimal: {0:d} 321545
321543.23 - Scientific: {0:e} 3.215432e+005
321543.23 - Fixed: {0:f3} 321543.230
321543.23 - General: {0:g} 321543.23
321543.23 - Number: {0:n} 321,543.23
321543.23 - Number with no decimals: {0:n0} 321,543
321543.23 - Number with 4 decimals: {0:n4} 321,543.2300
321543.23 - Percent: {0:p} 32,154,323.00 %
321543.23 - Percent with no decimals: {0:p0} 32,154,323 %
321543.23 - Percent with 4 decimals: {0:p4} 32,154,323.0000 %
321545 - Hex: {0:x} 4e809
321545 - HexFixed: {0:x8} 0004e809
9/22/2014 6:10:45 AM - Short date: {0:d} 9/22/2014
9/22/2014 6:10:45 AM - Long date: {0:D} Monday, September 22, 2014
9/22/2014 6:10:45 AM - Full (long date - short time): {0:f} Monday, September 22, 2014 6:10 AM
9/22/2014 6:10:45 AM - Full (long date - long time): {0:F} Monday, September 22, 2014 6:10:45 AM
9/22/2014 6:10:45 AM - General (short date - short time): {0:g} 9/22/2014 6:10 AM
9/22/2014 6:10:45 AM - General (short date - long time): {0:G} 9/22/2014 6:10:45 AM
9/22/2014 6:10:45 AM - Month Day: {0:m} September 22
9/22/2014 6:10:45 AM - RFC1123: {0:r} Mon, 22 Sep 2014 06:10:45 GMT
9/22/2014 6:10:45 AM - Sortable/ISO8601: {0:s} 2014-09-22T06:10:45
9/22/2014 6:10:45 AM - Short time: {0:t} 6:10 AM
9/22/2014 6:10:45 AM - Long time: {T} 6:10:45 AM
9/22/2014 6:10:45 AM - 's' but uses Universal time: {0:u} 2014-09-22 06:10:45Z
9/22/2014 6:10:45 AM - Universal sortable: {0:U} Monday, September 22, 2014 10:10:45 AM
9/22/2014 6:10:45 AM - Year Month: {0:y} September, 2014
9/22/2014 6:10:45 AM - All Days: {0:d dd ddd dddd} 22 22 Mon Monday
9/22/2014 6:10:45 AM - All Fractions: {0:f ff fff ffff fffff ffffff} 0 08 083 0832 08324 083243
9/22/2014 6:10:45 AM - All Eras: {0:g gg} A.D. A.D.
9/22/2014 6:10:45 AM - All Hours: {0:h hh H HH} 6 06 6 06
9/22/2014 6:10:45 AM - All Months: {0:M MM MMM MMMM} 9 09 Sep September
9/22/2014 6:10:45 AM - All Minutes: {0:m mm} 10 10
9/22/2014 6:10:45 AM - All Seconds: {0:s ss sss} 45 45 45
9/22/2014 6:10:45 AM - All AM/PM: {0:t tt ttt} A AM AM
9/22/2014 6:10:45 AM - All Years: {0:y yy yyy} 14 14 2014
9/22/2014 6:10:45 AM - All Timezones: {0:z zz zzz zzzz} -4 -04 -04:00 -04:00