If you face database performance issues, you might need some way to get running queries from there. SQL profiler is good, but some times you do not have it or you don't have access to it.
But if you can run SQL queries, you can use this script. It will show you immediate snapshot of all running queries.
If you are searching for statistical information you can use that query. This one will show you to 30 heaviest queries on the sever.
Have a nice development!