I have got a HP iPaq h2210.
I get my software mostly from http://pocketgear.com (you can download free trials of most of the programs on there which is handy) and http://www.handango.com see if there is any programs on there you like, if not you could try searching on google.
A program I find great is Innobec SideWindow (http://www.innobec.com/en/products.php) its a great program that lets you use your PDA as an extra monitor on your PC or laptop, I use it on my laptop as a media player remote controll, I leave my laptop in my bag and have the pda connected, then I drag the media player window across to the pda screen and plug my headphones in and it works really well (and i'm the talk of the college for that!)