On a three day business trip to Charleston I managed to get in a bit of birding (photos here: http://www.flickr.com/photos/breffni). As luck would have it, the hotel where the meeting was taking place was probably the best in the area for birding. Just a stroll in any direction from the hotel produced sparrows, warblers, terns, gulls, waders... This web site was an excellent reference -http://www.crbo.net/Charleston.html - the Hilton is now the Charleston Harbour Resort Hotel (where the meeting was). The article also refers to the Shine Inn - I think this is now the Quality Hotel. The locations are easy to find (beware of Charleston drivers though!) Given skipping off for a few hours Pitt St was probably the best - you can bird it in an hour and it produced ticks like wood stork and clapper rail.
Species seen on the trip include:
anhinga
double crested cormerant
yelow warbler
pine warbler
blue-grey warbler
yellow rumped warbler
yellow warbler (presumed)
ruby crowned kinglet
painted bunting
goldfinch
savannah sparrow
chipping sparrow
swamp sparrow
song sparrow
seaside sparrow
sharp-tailed sparrow
bank swallow
tree swallow
swift sp
house wren
marsh wren
mourning dove
ground dove
red-headed woodpecker
yellow bellied sapsucker
sharp shinned hawk
coopers hawk
red tailed hwwk
turkey vulture
black vulture
osprey
little blue heron
great blue heron
white ibis
snowy egret
great white egret
tricoloured heron
clapper rail
wood stork
belted kingfisher
snowy plover
semipalmated plover
killdeer
western sandpiper
short billed dowitcher
marbled godwit
willit
dunlin
sanderling
brown pelican
white pelican
forsters tern
franklins gull
herring gull
ring-billed gull
royal tern
forsters tern
black skimmer
Great! Even though migration was considered done and over with you seemed to accumulatle a great list.