You can have more indexes than columns..
Oracle allows you to have multi column indexes (indeed, in some situations, they are preferred). So, you could have an index for each column, and indexes for combo's of columns.
Whats the down side? More indexes means longer insert times, but frankly, this is far, far outweighted by the benefits.
Keep in mind, that table size is important, for small tables (and the def of small is open to interpretation
, an index may have no affect, or make access ever so slightly slower.