Links to other sites with Umbellifer interest

Images

Texas A&M Univeristy's Vascular Plant Image Gallery: Apiaceae (lots of images of cultivated and wild Umbellifers). 
Brousseau California Flora Photos: Apiaceae(lots of images of Californian Umbellifers). 
Wisconsin's Apiaceae pictures (gopher directory with several general Umbellifer images). 
University of Hawaii-Manoa Apiaceae pictures (a family description with several images). 
Albion College Apiaceae (and Araliaceae) pictures (only a few images). 
Apiaceae images at the Australian National Botanic Gardens (only a few images at present). 

Texas A&M University's Flora page has lots of information and links on many families of flowering plants. Search under Apiaceae from this start page. This site also includes a good overview of plant classification systems (Cronquist, Takhtajan and Thorne). 
DELTA descriptions of Umbelliferae (also has a few illustration, quotes, etc.). 
Cronquist family synonymy for Apicaeae (Index Nominum Supragenericorum Project). 
Flora Europaea Database, checklist for European species.
Synonymised Checklist of the Vascular Flora of the United States, Puerto Rico and the Virgin Islands: Apiaceae (BONAP/Texus A&M University).
Indices Nominum supragenericorum Plantarum Vascularium (University of Maryland), an alphabetical listing by genera of validly published suprageneric plant names.

USDA Ethnobotanical data for Apiaceae, lots of data on uses for many umbellifers, common names, etc.
GRIN database of Economic Plants (USDA), large listing of economic plants worldwide. 
USDA Carrot Genetics and Breeding Project (University of Wisconsin) has several useful links. 
US collection of carrot and its wild relatives, a basic links page 
Carrot fact sheet (University of Wisconsin) the history of domestication of the Carrot. 
Carrot fact sheet  (Oxford Forestry Institute) of Carrot crop data. 
Carrot fact sheet (Perdue University) of basic Carrot crop data 
Canadian Poisonous Plants Information System for Umbelliferae, good data on a few of the more common N American poisonous species.

Royal Botanic Garden Edinburgh, Living Plants Catalogue includes seedbank records. 
Collection data from the Flora of Costa Rica: Apiaceae
Apiaceae specimen data from the Flora of China
Endemic Apiaceae of Texas
Flora of Texus Consortium county map of Apiaceae and specimen listing 
Utah Apiaceae from the Utah Atlas at Utah State University
Apiaceae from Southern California from the Loyola Marymount
CalFlora Database family diversity map of Apiaceae

AGRICOLA: Umbelliferae or Apiaceae, US National Agricultural Library listing.

Umbelliferae Research at the Royal Botanic Garden Edinburgh

Internet Directory for Botany, an invaluable source of links to a  large number of  other sites
Dipsacales Research Website at Uppsala University.