A bit off-topic, but interesting for anyone trying to replace a real HP for a Palm OS calculator.
1. Free RPN calc
Type: scientific
Programmable: no
http://seul.org/~bergo/palm/rpn/
2. RPN 3.04
Type: scientific
Programmable: yes
http://www.nthlab.com/software/rpn/welcome.html
3. Neocal
Type: scientific, business, programmer
Programmable: yes
http://www.hudren.com/products/neocal/index.html
4. 2xcalc
Type: scientific, conversions
Programmable: no
http://www.palmgear.com/software/showsoftware.cfm?sid=34175820&prodID=2286
5. Mathu / MathuPro / RootM
Type: scientific, financial, complex (RootM)
Programmable: yes
http://www.creativecreek.com/
6. PowerOne
Type: scientific, financial
Programmable: yes
http://www.infinitysoftworks.com/
7. Kalk
Type: scientific
Programmable: no
http://www.palmgear.com/software/showsoftware.cfm?sid=34175820&prodID=365
8. Abacus
Type: Financial
Programmable: no
http://www.dovcom.com/abacus.html
9. Megacalc
Type: scientific, financial, conversions
Programmable: no
http://www.megasoft2000.com/palm_division/megacalc.htm
10. Hex Calculator
Type: programmer
Programmable: no
http://www.palmgear.com/software/showsoftware.cfm?sid=34175820&prodID=963
http://homepage.mac.com/w3woody/
11. Intcalc
Type: programmer
Programmable: no
http://www.inertron.com/palm/morepalm.html
12. CustomCalc
Type: scientific, financial
Programmable: no
http://www.visacsoft.com/mainns1024.html
13. Financial Consultant
Type: scientific, financial
Programmable: no
http://www.landware.com/financialconsultant/PALMOS/index.html
14. RPN Calculator
Type: scientific
Programmable: no
http://www.palmgear.com/software/showsoftware.cfm?sid=34175820&prodID=42434
15. RPNPopupCalc
Type: scientific
Programmable: yes
http://www.benc.hr/rpnpopcalc.htm