I-CON 27 (April 4-6, 2008) Stony Brook University, Stony Brook, NY. Author GoH: Charlaine Harris; Gallun Award Recipient: Ray Bradbury (virtual guest); IOCNOsphere Recipient: Harlan Ellison. Website: http://iconsf.org/
Odyssey Con 2008 (Apr 4-6, 2008) Madison WI. Radisson. GoHs: Kage Baker and George R. R. Martin. Details: see website http://www.oddcon.com/index.php
WillyCon IX (Apr 4-6 '08) Wayne State College Student Center, Wayne NE. Info: SF & F Club - WillyCon, c/o Ron Vick, Wayne State College, 1111 Main St., Wayne NE 68787; email: scfanta1@wsc.edu; website: www.willycon.com
CoastCon 31 (April 11-13, 2008) Missississipi Coast Coliseum and Quality Inn in Biloxi, Mississippi. Author GoH: David Gerrold. Other author guests include Glenda Finkelstein, Deborah LeBlanc, Deborra Wiles, Sharon Green, and Bob Liddil. Media guests include Gigi Edgley of Farscape and Peter Mayhew of Star Wars. Website for more details: www.coastcon.org.
2008 Williamson Lectureship Luncheon (Apr 11, 2008) Eastern New Mexico University Portales, NM. Guests include Steven Gould, Christopher Stasheff, Connie Willis. Lunch is followed by panels featuring the Lectureship guests and other visiting writers on SF in film and new directions in SF and fantasy. For information or reservations, contact Patrice Caldwell.
New York Comic Con (Apr 18-20 2008) Jacob Javits Center, New York City. Literary guests include Terry Brooks, Peter F. Hamilton, Naomi Novik. Details: http://www.nycomiccon.com/.
EerieCon Ten (Apr 18-20 2008) Days Inn at the Falls, Niagara Falls, NY. GoHs Sephera Giron, Joe Haldeman. Others: Robert J. Sawyer, Josepha Sherman, Nancy Kress, Edovan Belkom, Gay Haldeman, many more. Website: http://www.eeriecon.org/.
2008 NEBULA AWARDS WEEKEND (Apr 24-27 '08) Driskill Hotel, Austin TX. Info: website: www.sfwa.org/news/2006/2008nebulaweekend.htm
Costume-Con 26 (Apr 25-28 '08) DoubleTree Hotel San Jose, San Jose CA. Info: website http://www.cc26.info/
Ravencon 2008 (April 25-27, 2008) Crown Plaza West Hotel 6531 West Broad Street Richmond, Virginia 23230. Author GOH: C.S. Friedman ArtistGOH: Stephen Hickman Fan GOH: Filthy Pierre $25 until 9-30-07 $30 until 12-31-07 $35 until 4-18-07 $40 at the door. Young Adults (12-17) $15 Children (11 and under): FREE 10% Military Discount with military ID Day Rates: Friday: $15 Saturday: $25 Sunday: $15 Email: info (at) ravencon.com ; website: http://www.Ravencon.com/
ConGlomeration 2008 (April 18-20, 2008), Clarion Hotel and Convention Center, Louisville, KY. GOHs: Walter Koenig, A.C. Crispin, Eric Fortune, Michael Capobianco. Also artist Erik Appelhof, special performances by The Molly Maguires. Membership $30 until April 1, $40 thereafter and at the door. E-mail: info@conglomeration.org; Web site: http://www.conglomeration.org.
Fantasticon 2008 (April 26-27, 2008) Copenhagen, Denmark. GoHs: Norman Spinrad, Erwin Neutzsky-Wulff. Details: http://www.fantasticon.dk/fantasticon2008/english.php.

Source : http://www.locusmag.com/Conventions.html