Depends on which side of town (it's a big place):
On the west side:
Crafty Threads
12230 Race Track Rd
Tampa, FL 33626
http://craftythreads.com/
Just to the north of Tampa:
Scrap and Sew
16541 Pointe Village Dr #108
Lutz, FL 33558
http://www.scrapandsew.com/default.htm
(Scroll down for map/directions)
Middle (just west of downtown):
Hancock’s Fabric (not of Paducah)
1112 So Dale Mabry Hwy
Tampa, FL 33629
http://www.hancockfabrics.com/