Since lawyers aren't the only professionals who need to track their time and bill for it, there are a large number of products available. This software is used to capture case-related time and expenses, generate reports and bills, and integrate with accounting software.

Articles
Oh the Software You'll Find: Choosing the Right Time and Billing Software for Your Firm
Courtney Kennaday, South Carolina Lawyer, 2003.

Time and Billing software comparison chart
ABA Legal Technology Resource Center

 

Time and Billing Software and Services List

Cloud Based:

ActionStep http://www.actionstep.com/ (practice management includes time and billing)

BigTime http://www.bigtime.net (desktop widget available)

Bill4Time http://www.bill4time.com

CaseFox http://www.casefox.com/web/subscriptionplans.html

Clio http://www.goclio.com

Easy TimeBill http://bit.ly/SzRrc4

eBillity http://www.ebillity.com/time-billing-software/features/legal-billing-software

EnterYourHours http://www.enteryourhours.com/

FreshBooks http://www.freshbooks.com

GoMatters http://www.gomatters.com/

Harvest http://www.getharvest.com

iTimeKeep http://www.itimekeep.com/ 

LAWS Pro http://www.lawspro.com/

MyCase http://www.mycaseinc.com/

Overseer http://www.overseerlawofficesoftware.com

RocketMatter http://www.rocketmatter.com/

Time59 http://www.time59.com/

Times Manager http://www.timesmanager.com/legal-billing-software.html

WinYou Law http://www.winyou-law.com/

Zoho Invoice http://bit.ly/SzPQmA (mobile apps available)

 

 Desktop Based:

AbacusLaw http://www.abacuslaw.com

Amicus http://www.amicusattorney.com

Bamboo Invoice http://bambooinvoice.org/ FOSS Product

Billings (Mac only) http://www.marketcircle.com/billings/

BillingTracker http://www.billingtracker.com/

Chaos Software Legal Billing http://www.chaossoftware.com/legal-billing.aspx

Credenza Pro http://credenzasoft.com/pro.html

ESILaw http://www.esilaw.com

Easy TimeBill http://bit.ly/SzRrc4

fanurio (Mac & Windows) http://www.fanuriotimetracking.com

iBiz 4 (Mac only) http://www.iggsoftware.com/ibiz/index.php

HourGuard Timesheet Software http://bit.ly/SzWsS4 (NCH Software)

ImagineTime http://www.imaginetime.com (also has Doc mgmt, calendaring, and other products)

OfficeTime (Mac & PC) http:www.officetime.net/

PCLaw http://bit.ly/SzZ3ew

ProfitTrain (Mac only) http://clickablebliss.com/profittrain/

RTGBills http://www.rtgsoftware.com

Tabs3 http://tabs3.com

TaskTime4 (Mac only) http://www.ttpsoftware.com/Products/tasktime4.html

TimeNet Law (Mac only) http://www.applesource.biz/software/timenet-law/

Timeslips http://na.sage.com/Sage-Timeslips/

Tussman http://www.tussman.com/

List courtesy of Nerino J. Petro, Jr.