<ARTICLE> 5
       
                                                  
<PERIOD-TYPE>                   YEAR                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1996             DEC-31-1997
<PERIOD-START>                             JAN-01-1996             JAN-01-1997
<PERIOD-END>                               DEC-31-1996             SEP-30-1997
<CASH>                                      14,737,806              44,751,298
<SECURITIES>                                 4,857,163              22,897,196
<RECEIVABLES>                                3,275,518               4,350,464
<ALLOWANCES>                                   383,350                 688,572
<INVENTORY>                                     60,543                  66,029
<CURRENT-ASSETS>                            23,528,266              75,068,866
<PP&E>                                       3,462,153               6,953,498
<DEPRECIATION>                                 783,355               2,180,018
<TOTAL-ASSETS>                              26,468,158              84,371,634
<CURRENT-LIABILITIES>                        6,634,922              24,307,049
<BONDS>                                              0                 959,380
<PREFERRED-MANDATORY>                       23,153,494              49,277,652
<PREFERRED>                                     13,713                  13,713
<COMMON>                                           535                   1,543
<OTHER-SE>                                 (3,334,506)             (8,104,363)
<TOTAL-LIABILITY-AND-EQUITY>                26,468,158              84,371,634
<SALES>                                              0                       0
<TOTAL-REVENUES>                            14,012,388              22,416,804
<CGS>                                                0                       0
<TOTAL-COSTS>                                2,185,524               4,608,661
<OTHER-EXPENSES>                            15,843,408              27,567,116
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                                   0                       0
<INCOME-PRETAX>                            (3,789,245)             (8,574,716)
<INCOME-TAX>                                         0                       0
<INCOME-CONTINUING>                        (3,789,245)             (8,574,716)
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                               (3,789,245)             (8,574,716)
<EPS-PRIMARY>                                   (0.14)                  (0.32)
<EPS-DILUTED>                                        0                       0