what are you looking to do? If this is mainly for office based work and gaming, Benq's new 24inch TN based LCDs are pretty damn good. What is your budget. Most of the middle of the road 24inch LCDs that are not TN's but not S-IPS based do not exist any more.
In my opinion all TN panels represents the low end, S-PVA is middle, and the NEC LCD2490WUXi (the only IPS monitor) represent the high end.
If I wanted to spend the least amount of money for a good 24" monitor then I would by the HP LP2465 which uses a S-PVA panel. Pretty good user reviews over at Newegg.com.
If interested, don't buy it from Newegg.com. Instead, buy it from Provantage.com because of the $49 price difference. On top of that, HP also has a $50 mail-in rebate for the LP2465; it expires on Oct 31st.