<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   12-MOS                  12-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1996             DEC-31-1997             DEC-31-1998
<PERIOD-START>                             JAN-01-1996             JAN-01-1997             JAN-01-1998
<PERIOD-END>                               DEC-31-1996             DEC-31-1997             MAR-31-1998
<CASH>                                         775,865              10,686,001              60,521,171
<SECURITIES>                                   245,641               1,003,045                       0
<RECEIVABLES>                                  130,437                 180,312                 654,531
<ALLOWANCES>                                    12,000                  77,000                (89,564)
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                             1,201,764              14,471,415              63,594,451
<PP&E>                                         505,224               2,488,074               3,349,763
<DEPRECIATION>                                 143,189               (603,778)               (821,290)
<TOTAL-ASSETS>                               1,575,459              16,448,425              66,227,754
<CURRENT-LIABILITIES>                          970,309              15,689,420               7,452,953
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0               9,492,594                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                       579,549                 579,549              77,265,542
<OTHER-SE>                                    (65,532)            (10,331,999)            (19,576,558)
<TOTAL-LIABILITY-AND-EQUITY>                 1,575,459              16,448,425              66,227,754
<SALES>                                      6,300,294              17,372,795              10,013,889
<TOTAL-REVENUES>                             6,300,294              17,372,795              10,013,889
<CGS>                                        5,217,789              14,316,028               8,554,549
<TOTAL-COSTS>                                2,878,357              13,633,860              10,717,058
<OTHER-EXPENSES>                                     0                 201,650                 506,039
<LOSS-PROVISION>                                12,000                   5,000                       0
<INTEREST-EXPENSE>                              14,556               (371,962)               (446,515)
<INCOME-PRETAX>                             (1,810,408)           (11,157,508)             (9,198,193)
<INCOME-TAX>                                         0                       0                       0
<INCOME-CONTINUING>                        (1,810,408)            (11,157,508)             (9,198,193)
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                               (1,810,408)            (11,157,508)             (9,198,193)
<EPS-PRIMARY>                                        0                  (0.07)                  (0.78)
<EPS-DILUTED>                                        0                       0                       0
        

</TABLE>