If you are hosting your Magento store on shared hosting, this is almost required that you have to run re-index through command line. Even if you are on powerful server, you may find from time to time reindex times out if you have big data.
To over come this issue, you can use your command line to run reindex on required indexes.
I use PuTTY to connect to server and then go to your magento install and then to shell folder. e.g.
~/public_html/shell
Here you can check status of current indexes with this command:
Magento was not recording correct number of times a shopping cart coupon was used. When I ran below query in database, it was giving wrong information as far as I know.
mysql> select u.coupon_id, c.code, count(*) as total from salesrule_coupon_usage u, salesrule_coupon c where u.coupon_id=c.coupon_id and u.coupon_id IN (119, 132, 91) group by u.coupon_id;
May be I was wrong to use that query to find usage :), so tried another query, which gave me better report.